The figure originated with Everytown for Gun Safety, a nonprofit, co-founded by Michael Bloomberg, that works to prevent gun violence and is most famous for its running tally of school shootings.
This, the organization tweeted at 4:22 p.m., is the 18th school shooting in the U.S. in 2018.
Sen. Bernie Sanderss tweet including the claim has been liked more than 45,000 times, and one from political analyst Jeff Greenfield has cracked 116,000. New York City Mayor Bill de Blasio tweeted it, too, as did musicians Cher and Alexander William and actors Misha Collins and Albert Brooks. News organizations including MSNBC, ABC News, NBC News, CBS News, TIME, MSN, the BBC, the New York Daily News and the Huffington Post also used the number in their coverage. By Wednesday night, the top suggested search after typing 18 into Google was 18 school shootings in 2018.
It is a horrifying statistic. And it is wrong.