A yearlong investigation by The Trace and more than a dozen NBC TV stations identified more than 23,000 stolen firearms recovered by police between 2010 and 2016 — the vast majority connected with crimes. That tally, based on an analysis of police records from hundreds of jurisdictions, includes more than 1,500 carjackings and kidnappings, armed robberies at stores and banks, sexual assaults and murders, and other violent acts committed in cities from coast to coast.