Transmittal Letter


September 4, 1997






SUBJECT: Inspection of INS Monitoring of Nonimmigrant Overstays, Report Number I-97-08

In our continuing effort to address illegal immigration issues, we conducted an assessment of the Immigration and Naturalization Service's (INS) monitoring of nonimmigrant overstays and the Nonimmigrant Information System (NIIS).

We found that INS cannot identify individual overstays and, although INS has some demographic information on overstays, it cannot adequately describe the characteristics of the overstay population in the United States, such as countries of origin, occupations, or worksites where overstays are employed. This information would assist INS in developing an enforcement strategy that effectively targets overstays.

NIIS, INS's primary information system on nonimmigrants, is not producing reliable overstay data, either in the aggregate, or on individual nonimmigrants. By design, NIIS only captures information on about 10 percent of nonimmigrant entries. Canadians and Mexicans entering through land border ports-of-entry comprise over 90 percent of all nonimmigrant entries but are not tracked in NIIS. Furthermore, the data on the small portion of nonimmigrants that is tracked in NIIS is incomplete and unreliable due to missing departure records and incomplete records processing.

NIIS has not produced reliable data on the number of overstays by country of origin since Fiscal Year 1992. Without this data, INS is unable to perform its responsibilities for monitoring the Visa Waiver Pilot Program, including determining whether a country should be placed on probation or terminated from the program.

INS fails to effectively use other extensive overstay information at its disposal. Specifically, data gathered by INS during enforcement and benefits operations remains untapped. The results from our sampling of adjustment of status applications and apprehension records illustrate the potential value of this information in determining the characteristics of the overstay population. We suggest that INS periodically compile overstay data routinely captured by its benefits and enforcement operations into a form that is retrievable and useful for policy-making.

Although INS's estimates that overstays constitute 41 percent of the illegal alien population in the United States, INS's enforcement programs currently encounter relatively few overstays. Some changes in enforcement strategy, within existing programs, have the promise of leading to the arrest of more overstays. However, NIIS data is inadequate to enable INS to identify, locate, and arrest individual overstays.

Our report contains four recommendations that we believe will assist INS in monitoring nonimmigrant overstays and enhancing overstay enforcement. These recommendations include improving the collection of departure records for nonimmigrants, ensuring complete and reliable NIIS data, conducting an analysis of overstay data to support enforcement efforts, and developing an enforcement strategy that effectively targets overstays. We hope our comments, suggestions and recommendations in the attached report will be useful in your efforts to address these issues.

We sent copies of the draft report to your office on June 30, 1997, and requested written comments on the findings and recommendations. Your September 3, 1997, response addressed each of the four recommendations. We have attached your response as Appendix I.

On the basis of your written comments, we considered all recommendations unresolved and have kept them open pending further action. Appendix II explains why the recommendations were not resolved and what actions are needed.

Please respond to the recommendations by October 10, 1997. Your response should provide the additional information requested. If actions have not been completed, please provide projected completion dates. Guidance on report follow-up and resolution can be found in Department of Justice Order 2900.10.

We appreciate the cooperation extended to our Inspections Division staff during the review. If you have any suggestions how we might improve our review process, or if we can provide you with additional information, please let us know.


cc: Kathleen Stanley


Immigration and Naturalization Service

Vickie L. Sloan


Audit Liaison Office




The large number of foreign visitors who legally enter the United States and then do not leave presents a disturbing and persistent problem. Disturbing, because these visitors may be taking jobs and other benefits that by law are reserved for legal residents. Persistent, because the Immigration and Naturalization Service (INS) estimates that such visitors have accounted for a large part of the illegal alien population for many years and that this population is growing substantially each year.

INS estimates the current illegal alien population to be approximately 5 million. The common perception of illegal immigration is that illegal aliens enter the United States by surreptitiously crossing the Southwest border. In fact, INS officials have testified before Congress that 40 to 50 percent of the illegal alien population entered the United States legally as temporary visitors [ Testimony of Commissioner Doris Meissner before the Subcommittee on Commerce, Justice, State, the Judiciary, and Related Agencies of the Committee on Appropriations of the House of Representatives, May 8, 1996, and testimony of Executive Associate Commissioner for Programs James Puleo before the Subcommittee on Immigration and Claims of the Committee on the Judiciary of the House of Representatives, February 4, 1995.] but simply failed to depart when required. INS commonly refers to these illegal aliens as overstays.

Each year, millions of aliens enter the United States as temporary visitors, i.e., nonimmigrants (227 million in FY 1996). Over 90 percent are tourists or business visitors, but nonimmigrants also include students, temporary workers and diplomats. Most of these individuals leave the United States, but some do not. INS estimates that the resident illegal alien population in the United States increases by 125,000 overstays annually.

The number of alien overstays has increased with the growth of modern air travel and tourism. The available evidence indicates that overstays are a diverse population, whereas aliens illegally crossing the land border are primarily Mexican citizens. Some aliens, who are unable to obtain immigrant visas, manage to obtain nonimmigrant visas and come to the United States with the intention of staying. Other nonimmigrants may come with the intention of returning home, but once here, decide to stay. Regardless of their initial intent, once nonimmigrants have been legally admitted to the United States, they can stay legally until their terms of admission expire. During that time, they have several months in which to blend into the population.

Historically, the overstay issue has not been a primary consideration in the formulation and execution of immigration policy. However, the nature of the illegal immigration debate appears to have changed. Congress is interested in monitoring nonimmigrants and removing overstays. Several provisions in the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 are evidence of this interest, including a requirement for the development of an automated entry and exit control system to track nonimmigrant visitors to the United States. While there is increased interest in overstays, policy discussions are hampered by the lack of information on overstays.


No one really knows the actual number of overstays in the United States. Overstays do not advertise their unlawful presence and invite their arrest and removal. Of necessity, attempts to quantify overstay numbers have been indirect estimates, rather than direct counts. One source of data on the number and demographics of overstays is INS' study of the legalized alien population.

INS Study of Legalized Alien Population

INS' 1992 Report on the Legalized Alien Population provided some information on the demographics of the illegal alien population, including overstays. This study surveyed aliens who gained legal status under an amnesty provision of the Immigration Reform and Control Act of 1986 (IRCA). Section 245A of the IRCA allowed illegal aliens who lived in the United States continuously since January 1, 1982, to apply for legalization between May 5, 1987, and May 4, 1988. IRCA also mandated a report describing the general characteristics of the legalized population.

The report showed that the great majority of aliens from Europe, Asia, and Africa who were legalizing their status had overstayed. The overstays in the study were better educated, tended to have higher family incomes, and held white collar jobs at a higher rate than those aliens who had surreptitiously entered the United States (also known as entered without inspection or "EWI"). Of the overstays, 67 percent had over 12 years of education and 9 percent had 6 or fewer years of education. However, of the EWIs in the study, only 17 percent had over 12 years of education and 45 percent had 6 or fewer years of education. Twenty-nine percent of the overstays earned $30,000 or more, while only 17 percent of the EWIs earned as much. Thirty-four percent of all overstays fell into the lowest end of the earning scale (under $12,000 per annum) versus about 41 percent of the EWIs. Twenty-five percent of overstays, but only 8 percent of EWIs, held white collar jobs.

The study showed that the geographical concentration of overstays varied significantly. In California, Texas, and Illinois, overstays represented 19 to 22 percent of the legalized alien population. In New York and Florida, however, overstays were 48 and 69 percent of the legalized alien population, respectively. Overall, overstays were 24 percent of the legalized alien population. However, the aliens in the study may not be representative of the entire illegal alien population because some portions of the population may have been more or less likely to apply for legalization. Some INS officials with whom we spoke at headquarters and in the field believed that overstays may not have taken advantage of the IRCA amnesty to the same extent as EWIs. If overstays and EWIs did not apply at the same rates, any estimate of the overstay population based on the study would be skewed.

Another limitation of the legalization study as an indicator of the resident overstay population is that it only surveyed aliens who entered the United States before 1982 and continued to reside here until they applied for legalization. INS Statistics Division personnel believe that overstays depart and adjust status [ Adjustment of status is a procedure allowing certain aliens already in the United States to apply for legal permanent residence. ] at higher rates than EWIs. During the years that elapsed since those applying for legalization had entered the country, INS officers speculate that the percentage of overstays in the resident alien population may have declined due to higher rates of departures and adjustments of status.

INS Estimates of the Illegal Alien Population

The most comprehensive effort to estimate the size of the illegal alien population residing in the United States was completed by the INS Statistics Division in 1994. [ "Estimates of the Undocumented Immigrant Population Residing in the United States by Country of Origin and State of Residence as of October 1992," Robert Warren, Statistics Division, U.S. Immigration and Naturalization Service.]

This 1994 estimate was the culmination of a 20-year effort to reliably measure the illegal alien population residing in the United States. The estimate was derived from demographic analyses of census data, data on aliens who legalized under the amnesty provisions of IRCA, and data from INS systems, including the Nonimmigrant Information System (NIIS).

The 1994 Statistics Division Study was updated by the INS Office of Policy and Planning in 1997. The 1997 updated estimate was based on an adjustment of INS' earlier methodology from its 1994 study on the illegal alien population, including the incorporation of new data from the Census Bureau's Current Population Survey. The updated estimate of the resident overstay population was based primarily on identifying trend changes in the number of overstays from FYs 1982 through 1992 and projecting those trends to the present. This estimate used no NIIS data from the years since FY 1992 because INS' Office of Policy and Planning and the Statistics Division believed that NIIS overstay data for these years was unreliable. The problems with the NIIS data are discussed later in this report.

INS' latest estimate is that, as of October 1996, the illegal alien population residing [ The study defines a resident illegal alien as an alien who has remained in the United States for more than 12 months in an illegal status. ] in the United States was about 5 million and was growing by about 275,000 per year. INS estimated that 41 percent of the resident illegal alien population consisted of aliens who had entered the country legally and failed to depart, i.e., overstays. [ INS' updated estimates calculate a margin for error of plus or minus 8 percent for the total resident illegal alien population and plus or minus 6 percent for the resident overstay population. ] The remaining 59 percent were EWIs. INS estimated that the number of resident overstays was growing by 125,000 each year and the number of resident EWIs was growing by 150,000 each year.

INS Apprehension Data

Another source of overstay data is the nationwide enforcement statistics compiled by INS in its Report of Field Operations. Part G-23.18 of this report provides data on the status at entry of deportable aliens apprehended. Aliens arrested are categorized as EWIs, status violators (mostly overstays) and immigrants (mostly arrested for criminal offenses). The Report of Field Operations (Table 1) shows that INS investigators apprehended approximately 10,000 overstays each year for FYs 1992 through 1996. [ INS investigators, working in the investigations divisions of INS district offices, conduct most alien arrests in the interior of the United States. While the Border Patrol arrests more than 1 million aliens per year, these aliens are primarily EWIs arrested along the border. ] During this same period, the number of EWIs apprehended annually by INS investigators increased from 41,753 to 80,367. As a percentage of illegal aliens apprehended, overstays ranged from a high of 19.8 percent in FY 1992 to a low of 11.1 percent in FY 1996. [ The G-23.18 shows an alien's status at entry rather than status when apprehended. The report breaks out the status at entry among immigrants, EWIs, and other categories such as visitors, students, and crew members. In computing the number of overstays apprehended, we assumed that all deportable aliens apprehended other than immigrants and EWIs were overstays. Thus, the numbers presented here actually represent the maximum possible number of overstays apprehended. INS officials concurred that this method would compute the maximum number of overstays apprehended.] Although the percentage of overstays apprehended declined, the absolute number remained relatively constant at about 10,000 per year. The decline in the percentage is due to the increase in the numbers of EWIs

Table 1: Deportable Aliens Apprehended by Investigations [ INS Investigators also apprehended 6,000 to 8,000 immigrants in each of the above fiscal years, most of whom were deportable for criminal activities.]

FY 1992 FY 1993 FY 1994 FY 1995 FY 1996
EWIs 41,753 43,873 43,851 52,351 80,367
Overstays 10,301 10,023 10,189 10,197 10,084
Total 52,054 53,896 54,040 62,548 90,451
Percent Overstays 19.8% 18.6% 18.9% 16.3% 11.1%

Source: INS Report of Field Operations, Form G-23.18

apprehended. The percentage of overstays apprehended is less than one would expect, given INS' estimate that overstays make up 41 percent of the illegal alien population.

INS Removal Data

Another source of information on overstays is INS' Deportable Alien Control System (DACS). This system contains data on aliens for whom deportation proceedings have been initiated. Aliens apprehended by the Border Patrol along the Southwest border who voluntarily leave the United States are not included in DACS. As with the apprehension data, the percentage of overstays removed is less than one would expect given INS' overstay estimate (Table 2). [ Like the G-23.18, DACS shows an alien's status at entry rather than status when apprehended. In computing the number of overstays removed, we assumed that all deportable aliens removed other than immigrants and EWIs were overstays. Thus, the numbers presented here actually represent the maximum number of overstays removed.]

OIG Review of Apprehension Reports

In order to better understand the characteristics of the overstay population we visited four of INS' larger districts: New York, Chicago, San Francisco and Miami. We selected these districts based on indications that each had a relatively large number of overstays in its alien population. We interviewed adjudications and investigations

Table 2: Aliens Deported or Required to Depart [ The figures in this table do not include the number of exclusions because excluded aliens are neither overstays, nor EWIs. An exclusion is a formal denial of an alien's entry into the United States made by an immigration judge after an exclusion hearing. Also, the figures in this table do not include the 2,000 to 3,000 immigrants deported or required to depart under docket control, most of whom were removed for criminal activities.]

FY 1992 FY 1993 FY 1994 FY 1995 FY 1996
EWIs 37,305 35,192 36,994 38,122 44,987
Overstays 6,207 5,573 5,691 4,750 5,212
Total 43,512 40,765 42,685 42,872 50,199
Percent Overstays 14.3% 13.7% 13.1% 11.1% 10.4%

Source: Deportable Alien Control System

managers in each district and tested samples of documents relating to adjustments of status and apprehensions.

We took a random sample of Forms I-213, Records of Deportable Aliens Located, to measure the extent to which overstays might be involved in criminal activity and unauthorized employment (Table 3). In FY 1995, the four districts we visited accounted for slightly over 20 percent of the deportable aliens apprehended by INS investigators. In these districts, INS encountered overstays in the worksite enforcement and criminal alien programs at a much lower rate than it estimates overstays are present in the illegal alien population.

INS officials believe that EWIs are primarily unskilled laborers and tend to cluster in service industries. They believe overstays, on the other hand, are generally more highly skilled and dispersed throughout the economy. Most worksite enforcement cases are lead-driven, that is, based on tips received that particular businesses are employing illegal aliens. Further, INS investigators generally direct their resources at locations where they can apprehend the most illegal aliens at one time. Consequently, they tend to find mainly EWIs. INS investigators also stated that the higher education and income of overstays might make overstays less likely to commit criminal acts.

Table 3: Rate of Overstays in INS Investigations Arrests [ The universe from which our samples were taken consisted of FY 1995 and 1996 arrests by the criminal alien branch and the employer sanctions branch of each INS' district office we visited. The criminal alien branches determine the alien age of inmates at local, state and federal correctional facilities and initiate deportation proceedings when appropriate. They also participate in various local, state and federal task forces, such as those targeting violent gangs. The employer sanctions branches arrest aliens found illegally employed and enforce civil and criminal penalties against employers who knowingly hire aliens unauthorized to work in the U.S. ]

Undisplayed Graphic

Source: Records of Deportable Aliens Located, Forms I-213

OIG Review of Adjustment of Status Applications

In each of the four districts that we visited, we also examined a sample of applications from aliens adjusting status under Section 245(i) of the Immigration and Nationality Act. This provision allows certain aliens illegally present in the United States, who are otherwise eligible for immigrant visas, to apply for legal permanent

residency for a fee of $1,130. [ The total fee for adjustment of status under Section 245(i) was changed from $780 ($130 adjustment of status application fee plus a $650 surcharge) to $1,130 ($130 fee plus $1,000) by Section 376 of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996. Prior to the enactment of Section 245(i), an overstay had to depart the U.S. and then apply for an immigrant visa in order to become a legal permanent U.S. resident. ] Each application for adjustment of status indicates the alien's method of entry into the United States and status at the time of application.

Our sample shows overstays as a percentage of illegal aliens filing for adjustment of status while INS' 1992 Report on the Legalized Alien Population shows the percentage of overstays in the legalized alien population. Adjustment of status under 245 (i) and the legalization program are comparable in that they both grant legal permanent residence to aliens who were illegally present in the United States. Although neither our sample nor the 1992 legalization study definitively shows the actual percentage of overstays in the illegal alien population, both serve as indicators of it.

Our sample of over 400 adjustment of status applications produced results somewhat different from those of the 1992 legalization study (Table 4). In New York,

Table 4: Percentage of Overstays Among Aliens Adjusting Status [ The Report on the Legalized Alien Population did not isolate the percentage of overstays among aliens legalizing their status in San Francisco. The figure shown above is the percentage of overstays legalizing their status in California, excluding Los Angeles, Riverside and Anaheim. ]

Undisplayed Graphic

Source: OIG Inspections research based on Form I-485, Application to Register Permanent Residence or Adjust Status

Chicago and San Francisco, we found overstays applying for adjustment of status at about half the rate reported in INS' legalization study. In Miami we found a 66 percent overstay rate among aliens adjusting status under 245(i), while the legalization study reported a 69 percent overstay rate.

Summary of the Numbers

INS' estimate that overstays comprise 41 percent of the resident illegal alien population reflects a considerably higher percentage of overstays than is found in other sources of overstay data. These sources include INS' 1992 Report on the Legalized Alien Population, INS' Report of Field Operations, INS' Deportable Alien Control System, and our samples of arrest records and adjustment of status applications. If INS' estimate is accurate, then two possible explanations for this inconsistency are that overstays may be disproportionately under-represented in working, criminal and 245(i) populations, and INS enforcement operations may be more effective at locating EWIs than overstays.

INS' estimate is based on the most comprehensive analysis done to date of the resident illegal alien population. We reviewed the methodology of INS' estimate, and found that, although some of its underlying assumptions may be debatable, it appears reasonable based on the limited data available to INS' Statistics Division. Developing good overstay statistics is significantly hampered by deficiencies in INS' record-keeping system for tracking nonimmigrants who enter and depart the United States.


The principal INS record-keeping system for nonimmigrants is the Nonimmigrant Information System (NIIS). By design, NIIS only captures data on about 10 percent of all nonimmigrant entries--those entering through airports and seaports, and some of those entering through land border ports of entry. Because Canadians and Mexicans crossing at land borders are generally exempt from the Form I-94 requirement, and because they constitute 90 percent of nonimmigrant entries, NIIS contains arrival and departure information on only a small portion of nonimmigrants. [ Mexican nationals crossing at the Southern land border are required to have a Border Crossing Card. The requirements for obtaining a Border Crossing Card are similar to those for obtaining a visa.] In FY 1995, INS counted approximately 236 million nonimmigrant entries into the United States. Of these, NIIS contains information on only 22.9 million entries. Furthermore, the NIIS data on nonimmigrant entries is incomplete and unreliable due to missing departure records and incomplete records processing.

INS created NIIS in 1983 to automate the storage and retrieval of nonimmigrant information. Total NIIS operating costs are over $20 million each year. [ Cost data was provided by INS and was not verified by the OIG.] NIIS data on nonimmigrant arrivals is used to produce the nonimmigrant section of INS' Statistical Yearbook and is provided to the travel and tourism industry. [ Published information includes aggregate data on class of admission, country of citizenship, port of entry, and state of intended temporary residence in the United States.] INS employees query NIIS, as well as other INS systems, to determine an alien's status. Information on confirmed overstays (aliens for whom INS has received a departure record showing that the aliens left the country after their required departure dates) is entered into an interagency lookout system. This data may be used by consular officers of the State Department if overstays apply for subsequent visas, or by INS inspectors if overstays attempt re-entry into the United States.

NIIS is a relatively simple system. The Arrival/Departure Record, Form I-94, is the primary source of information for NIIS. Each Form I-94 contains a unique admission number and is perforated to form an arrival and departure portion. The admission number, which INS uses to record the arrival and departure of nonimmigrants, is printed on both portions.

Most nonimmigrants completing Forms I-94 do so en route to the United States. They present the forms to immigration inspectors who review the forms when inspecting the arriving aliens. The immigration inspectors retain the arrival portions and the aliens retain the departure portions. The departure portions are collected by transportation carriers and turned over to INS upon the aliens' departure.

INS forwards both the arrival and departure portions of the Forms I-94 to a contractor who keys the data from the forms. A second contractor receives the data, performs quality control procedures, and uploads the information into the NIIS database.

NIIS does not contain departure records for a large number of aliens, most of whom INS believes have left the United States. INS believes most of these unrecorded departures result from either the failure of airlines to collect Forms I-94 from departing nonimmigrants; or from nonimmigrants departing through land borders. However, an unknown number of unrecorded departures are due to other factors such as data entry keying errors, and the failure of the system to properly match arrival and departure records. Also, in the past, some records were lost through electronic transmission or through tape-loading problems. INS collectively refers to these factors and missing Forms I-94 as "system error."

In FY 1992, the last year for which the INS Statistics Division considers NIIS data reliable for overstay calculations, INS collected 20.5 million arrival records. At the time INS made its computations, the period of legal admission had ended for 19.9 million of these aliens and they should have departed the United States. However, INS was able to match departure records to only 18.2 million of the arrival records. The difference between 19.9 million and 18.2 million is, in theory, the number of individuals who failed to depart from the United States. INS refers to these individuals as "apparent overstays." INS estimated, however, that in FY 1992 only 300,000, and not 1.7 million nonimmigrants overstayed. The remaining 1.4 million nonimmigrants, were individuals who INS believed left the United States, but for whom no departure record was matched to an arrival record (Table 5). The number of apparent overstays has increased significantly since FY 1992.

Table 5: Apparent Overstays

FY 1992 FY 1993 FY 1994 FY 1995
Total I-94 Arrivals Collected 20,521,000 21,711,924 22,307,886 22,902,348
In Status [ "In status" includes those nonimmigrants who are not yet required to depart because their terms of admission have not expired. ] 599,000 771,539 607,796 729,298
Number Expected to Depart 19,922,000 20,940,385 21,700,090 22,173,050
Departure Forms Matched to Arrivals 18,244,000 18,700,060 18,749,866 17,289,289
Unmatched Arrival Forms (Apparent Overstays) 1,678,000 2,240,325 2,950,224 4,883,761
Percent of Apparent Overstays 8.4% 10.7% 13.6% 22.0%

Source: NIIS

To adjust for unrecorded departures, INS has developed a methodology to estimate actual overstays. First, INS computes the percentage of unrecorded departure records for 11 index countries believed to have negligible overstay rates. The methodology is based on the assumption that the percentage of unrecorded departure records for these index countries approximates the percentage of the overall system error. INS then develops its global overstay estimate by subtracting the system error from the total number of unrecorded departure records.

The INS Statistics Division discovered problems beginning with the FY 1993 NIIS data. Apparent overstay rates for certain classes of admission, such as visa waiver entrants, rose significantly over those of the prior year. Further, there were unusual and unexplainable fluctuations in apparent overstay rates by class, month of admission, and country of admission when compared to prior years. The Statistics Division concluded that, due to these fluctuations and comparatively high rates of apparent overstays, NIIS information after FY 1992 was unreliable for estimating overstay rates.

INS redesigned NIIS in 1996 to make the system more user friendly and address a number of problems. While it is too early to fully evaluate the redesigned system, incomplete records processing appears to be a continuing problem. Information received from the contractor performing NIIS quality control shows that for the 3-month period October through December 1996, 6.4 percent of the records received from the data entry contractor were rejected in the pre-load edit. The pre-load edit examines critical fields to ensure that data are present and valid. [ There are seven critical fields in which an omission or error will cause a record to be rejected (admission number, first name, last name, date of birth, country of citizenship, date of arrival, and class of admission). ] Additionally, 5.9 percent of the records that had passed the pre-load edit were rejected during loading. The loading process compares each new record to those already in the system and does not load those with admission numbers that are already in the system. [ Arrival records are rejected if the same admission number has been used for a previous arrival record, regardless of whether the nonimmigrant's name is the same on both records. Similarly, departure records are rejected if the same admission number has been used for a previous departure record.]

We reviewed a sample of 1,106 arrival records rejected during the loading process and found that 98.3 percent of those were rejected because the same admission number for the same person was already in the system. Most of the other records were rejected because the same admission number had been used for a different person. We also reviewed a sample of 1,050 departure records rejected during the loading process and found that 96.8 percent of those were rejected because a departure record for the same admission number and person was already in the system. It appears the data entry contractor submitted the same records twice, the contractor performing quality control tried to enter the same records twice, or nonimmigrants reused the same admission numbers on multiple entries into the United States. [ Prior to the redesign of NIIS, students were required to use their original admission numbers if they left and reentered the U.S. ]

The Statistics Division waits 9 months after the end of a period before computing overstay rates for the period. This 9-month interval gives visitors who entered in that period time to leave the country (most visas are limited to 6 months), eliminates short-term overstays from the numbers, and provides time for all departure records to be entered into NIIS. The Statistics Division has not yet analyzed FY 1996 overstay data and it is not known whether the NIIS redesign has solved any problems relating to the unreliability of the data, or whether NIIS will provide usable overstay data for FY 1996. However, in March 1997 INS' Office of Information Resource Management organized a cross-departmental group of NIIS users into a Process Action Team to address the problems with NIIS.