Data for this study were obtained from a variety of sources, including gun trace data from the Bureau of Alcohol, Tobacco, and Firearms, reports by the General Accounting Office and the Departments of Justice and Treasury, news reports from wire services, information from gun show publications, and data obtained from the Internet sites of the National Rifle Association and the National Association of Arms Shows. Three major findings emerged from the analysis of the data. First, States that do not require criminal background checks at gun shows are flooding the Nation with crime guns. In every State that traced at least 500 crime guns in 1999, most, if not all of the top sources of out-of-State crime guns were States that did not require background checks at gun shows. Second, since passage of the Brady Law, investigations point to gun shows as a major crime-gun source. According to the Bureau of Alcohol, Tobacco, and Firearms, from 1996 to 1998, gun shows were the Nation's second leading source of guns recovered in illegal gun trafficking investigations, accounting for 26,000 illegal firearms. Third, closing the gun show loophole would not adversely affect the gun show business. The National Instant Check System is virtually instant. Seventy-two percent of background checks are completed within several minutes, 95 percent within 2 hours, and only 1 in 30 background checks lasts more than a day, according to 2 government studies. Those potential buyers who are not approved in a day are 20 times more likely to be rejected for having a felony or other disqualifying record than those whose background check is concluded within 24 hours. Further, between 50 percent and 75 percent of firearms vendors at gun shows are licensed dealers who already must perform background checks under the law. This report thus concludes that requiring background checks at gun shows will not affect the millions of enthusiasts who attend gun shows each year, but is clearly an essential part of a comprehensive strategy to make it more difficult for criminals to obtain guns. 1 table and 2 figures