A charred piano. A singed light fixture dangling by a cord in a fire-scarred room. Plates strewn with ash, not far from a dinner table just cleared from a Passover Seder.

The scorched rooms inside the official residence of Gov. Josh Shapiro of Pennsylvania were the work of an arsonist who the authorities say admitted “harboring hatred” for Mr. Shapiro. Officials say the suspect revealed that if he found the governor, he planned to beat him with a hammer.

The attack on Mr. Shapiro and his family was only the latest prominent attempt on the life of an American elected official. A string of violent outbursts in recent years has raised alarms about the threats lawmakers are confronting and the country’s often poisonous political environment.

President Trump faced two assassination attempts last year, a bullet grazing his ear at a rally in Pennsylvania. A group of extremists planned to kidnap Gov. Gretchen Whitmer of Michigan. A man broke into Representative Nancy Pelosi’s home and assaulted her husband with a hammer. A gunman attacked Republican members of Congress as they practiced for a baseball game, wounding Representative Steve Scalise of Louisiana.

Yet while the attacks on top officials have rattled Americans in both parties, research shows that political violence overall is not necessarily on the rise. Large-scale eruptions — with the notable exception of the Trump-inspired riot at the Capitol on Jan. 6, 2021 — have not become more frequent. Support among Americans for acts of political violence like murder or arson remains exceedingly low, according to a weekly study conducted by the Polarization Research Lab at Dartmouth College.

“The high-profile nature of the attacks definitely makes it so that the public perceives political violence as a threat to the country that is disproportionate to the actual nature of the problem,” said Sean J. Westwood, a professor at Dartmouth College and the director of the Polarization Research Lab.