D.C. United–Philadelphia Union rivalry

The D.C. United–Philadelphia Union rivalry or the Union–United rivalry (sometimes referred to as the Colonial Cup or the Shertz–Gemmell Cup) is a soccer rivalry between D.C. United and the Philadelphia Union, who both play in the Eastern Conference of Major League Soccer. One of the several I-95 derbies, the two clubs began playing against each other regularly since 2010, when Philadelphia Union entered MLS as an expansion team.

Source: Wikipedia — D.C. United–Philadelphia Union rivalry (CC BY-SA 4.0)