"The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) National Tracing Center (NTC) is the nation's only crime gun tracing facility. As such, the NTC provides critical information that helps domestic and international law enforcement agencies solve firearms crimes, detect firearms trafficking and identify trends with respect to intrastate, interstate and international movement of crime guns. For calendar year (CY) 2010, the NTC traced over 285,000 firearms; CY 2011, over 319,000 firearms; CY 2012, over 332,000 firearms; CY 2013, over 336,000 firearms; CY 2014, over 351 ,000 firearms; and CY 2015, over 364,000 firearms. Over this time period the NTC has traced firearms for the United States and 127 countries. Firearms tracing is the systematic tracking of the movement of a firearm from its first sale by a manufacturer or importer through the distribution chain in an attempt to identify the first retail purchaser in order to provide investigative leads for criminal investigations. After the firearm is recovered and the identifiers are forwarded to the NTC, ATF contacts the manufacturer or importer to ascertain the sale or transfer of the firearm. ATF will attempt to contact all ensuing Federal firearms licensees (wholesale/retail) in the distribution chain until a purchaser is identified or the trace process cannot continue due to a lack of accurate or incomplete information on the trace request or in the Federal firearms licensee's records. The success of a trace result, whether domestic or international, relies upon the accuracy of the supplied firearm identifiers. The necessary identifiers for a trace include manufacturer, importer (if applicable), model, caliber and serial number. The report relates only to firearms recovered in Central America and traced by ATF. The firearm trace results are based upon the supplied firearm identifiers on the Central America trace requests. The Central American trace data in this report is organized by the calendar year in which the respective authorities report the firearm was recovered, not the year in which the trace was initiated. For example, if El Salvadorian authorities recovered a firearm in 2015 but the trace was not initiated until 2016, the data will be organized in the year of recovery, 2015. Organization by recovery date provides valuable investigative leads as well as more specific trend data. Therefore, using this example, if a firearm for which a trace is initiated in later years is determined to have been recovered in 2015, the raw trace numbers for 2015 will increase in subsequent trace data reports. As a result, the trace numbers for each calendar year may fluctuate, necessitating changes to prior years' trace numbers in future reports. If a recovery date is not provided for a firearm, trace data for that firearm is organized by the calendar year in which the trace was entered into the Firearms Tracing System by ATF."
United States. Bureau of Alcohol, Tobacco, and Firearms: https://www.atf.gov/