Minnesotans awoke on a recent Saturday to reports that an assassin had spent the night ticking his way down a list of Democratic targets, wounding one state lawmaker and his wife and then, just as the police closed in, killing another, along with her husband and their dog.

It was shocking. But it quickly seemed to become just another episode in a recent spate of political violence. Since last July, two people have tried to assassinate Donald J. Trump, an arsonist set fire to the Pennsylvania governor’s mansion while the family slept, an assailant fatally shot a couple leaving the Capital Jewish Museum in Washington and a man was charged with attempting to kidnap the mayor of Memphis.

The result is a troubling sense that political violence has become more brazen, and its motives more difficult to comprehend. The increase is not just public perception; experts agree that attacks on political figures have been increasing.

The Armed Conflict Location & Event Data project, a nonprofit that tracks conflicts around the globe, has recorded 21 acts of violence against politicians, their families or their staffs in the United States since it began counting them in 2020. A vast majority have occurred since 2022.

The rise comes as vicious and dehumanizing language and images become common in American politics. Online culture is a potent vector, seeming to only amplify rather than calm or contextualize, while offering plenty of encouragement to would-be imitators. And guns have been deregulated in many states, becoming easier to acquire.

Political violence can encompass a broad range of actions, from torching Tesla charging stations to premeditated sniper attacks, making it difficult to quantify.