This Tuesday, voters in Los Angeles head to the polls to pick a new mayor. And last Friday, Michigan Governor Rick Snyder announced his decision to appoint a manager with far-reaching powers over Detroit’s finances. It’s as good a time as any to consider the impact that mayors can actually have on city spending—and the limits of that influence. That’s what I do in a post over at Wonkblog. There might not be a Republican or Democratic way to pick up the trash, but mayors do have a pronounced influence on public safety, an area on which their authority is relatively uncontested.