A large and growing share of the American public turns to Facebook for news. On this platform, reports about crime increasingly come directly from law enforcement agencies, raising questions about content curation. We gathered all posts from almost 14,000 Facebook pages maintained by US law enforcement agencies, focusing on reporting about crime and race. We found that Facebook users are exposed to posts that overrepresent Black suspects by 25 percentage points relative to local arrest rates. This overexposure occurs across crime types and geographic regions and increases with the proportion of both Republican voters and non-Black residents. Widespread exposure to overreporting risks reinforcing racial stereotypes about crime and exacerbating punitive preferences among the polity more generally.