Challenger Corey O’Connor ousted Pittsburgh Mayor Ed Gainey in Tuesday’s Democratic primary election, beating an incumbent in a race that hinged on how Gainey was handling city finances, affordable housing and public safety.

It's Election Day and four candidates are looking to be selected to represent their party with the goal of being elected mayor of Pittsburgh in November.

Four things to know about the Pittsburgh mayoral race and what it could mean for the rest of Pennsylvania and the Democratic Party.