While Congress has not passed new gun restrictions after public mass shootings in recent years, hundreds of measures have passed in statehouses across the U.S., reports the Washington Post. Since the Columbine High School massacre in 1999, high-profile mass shootings have been followed by a jump in state gun-control laws in the next year or two years, finds an analysis of data on state legislation compiled by RAND. In 2013, nine states and Washington, D.C., enacted more than 40 gun-control laws in the year after deadly shootings in Newtown, Ct., and Aurora, Co. Since the Sandy Hook shooting in Newtown, 165 laws that restrict gun rights and 39 laws that expand gun rights have passed. During that time, only six states failed to pass any form of gun legislation — Indiana, Michigan, Montana, Ohio, Tennessee and Pennsylvania. The data show these new laws mostly come from statehouses controlled by Democrats, typically when a Democrat is also serving as governor. The data also suggest a countertrend. In states controlled by Republicans. Successful campaigns to restrict gun rights have at times set off reactions, which lead to laws that expand the rights of gun owners and chip away at existing gun-control measures. Those laws tend to pass when there is a lull in high-profile mass shootings. The data show how red and blue states in an increasingly polarized nation are taking diametrically opposed approaches to the same core problems, a trend that may be happening in statehouses since the latest mass shootings. At the time of the Buffalo and Uvalde massacres, most state legislatures had already recessed for the year, but at least five active legislatures have substantial gun-control packages under consideration. This month, New York became the first and only state so far to pass gun-control measures in direct response to the mass shootings.