Why is Dolton (Illinois) mayor Tiffany Henyard frequently referred to as "supermayor"

It's a self-chosen moniker that the press has latched onto in a mainly mocking way.

She labeled herself supermayor as a serious title and the press ran with it because she's so goddamn corrupt and bad at her job(s).

Seriously, you should look into the shit she's caused for that town. She didn't pay the bill for the city's leased cop cars, so they might all get repo'd. She hired out private security from the police force to do things like walk around her small town and hand out water bottles door-to-door on a hot day. She's taken first class flights to Vegas and stayed in 5-star hotels on the city's dime. She leased herself a 90k SUV also on the city's dime. She tricked people would showed up for a meeting concerning her performance in a basement so they wouldn't be able to speak at the meeting. She refused buisness and alcohol licenses to local buisness owners who spoke out against her or declined to donate to her.

...she may have put a hit out on another local politician she doesn't like.