Pittsburgh is the only city in which all three of its pro teams wear the
same colors--black and gold.

Pittsburgh is among the only cities that have pro teams that wear the same
colors. Each professional sports team, the Major League Baseball (MLB)
Pittsburgh Pirates, National Football League (NF) Pittsburgh Steelers, and
National Hockey League (NHL) Pittsburgh Penguins, from the Pennsylvania
city has the same official team colors of black and gold. The color scheme
is in reference to Pittsburgh’s black and gold city flag. However, only
the Pittsburgh Steelers have always been black and gold. The Pittsburgh
Pirates baseball team colors were red and blue from 1887 to 1947, while the
Pittsburgh Penguins hockey team colors have ranged from blue and gold to
red and gold from the 1920s until 1980.