Mayor Satya Rhodes-Conway’s inbox makes abundantly clear how personally venomous local politics has become.

“‘Fat,’ ‘sick,’ ‘worthless,’ ‘gutless,’ ‘loser,’” she said, reciting some of the insults that have been leveled at her since becoming mayor of Madison, Wis., in April.

She got a taste of the animosity during her campaign, when she was criticized on blogs and social media not for her plans for housing, stormwater management or transportation, but for not wearing makeup.

“People are angry, or afraid, and express themselves in mean ways,” she said.

Ms. Rhodes-Conway is not alone in facing this type of abuse. As many as 79 percent of mayors in the United States report being the victim of harassment, threats or other psychological abuse, according to a recent study. Thirteen percent also reported instances of physical violence.