[14] The finalization of the club was the result of a $47 million package approved by Delaware County politicians and Pennsylvania governor Ed Rendell that included the cost of Subaru Park and a major urban renewal project.

[15] Ahead of the 2010 Major League Soccer season, both clubs were pitted in the Eastern Conference of MLS and played each other twice: one home and one away leg, marking the first meetings between the Union and United.

The rivalry's roots can be traced back to the Union's first-ever home match on April 10, 2010, a 3–2 victory over D.C. United in front of 35,000 fans at Lincoln Financial Field in Philadelphia.

Later that season, the Union secured a crucial home win with a brace from Le Toux and a goal from Michael Farfan, pushing Philadelphia closer to its first playoff appearance.

That game featured notable incidents, including a missed penalty by Dwayne De Rosario, adding to the tension between the sides.

The rivalry continued to build as the teams clashed in both league play and the U.S. Open Cup, with each match proving highly competitive.

Philadelphia secured a memorable stoppage-time victory at home, while also advancing in the U.S. Open Cup after defeating D.C. United despite being reduced to 10 men.

D.C. United, however, managed to earn some key wins at home, including a come-from-behind victory in July 2015 after trailing by two goals.

[1] Ultimately, the fan poll on X, then called Twitter, resulted in the "Colonial Cup" being the winner,[20] although the rivalry is rarely referred to as that term.

In addition, United won the 1998 Copa Interamericana, an infrequently-held and now-defunct super cup between the champions of CONCACAF and CONMEBOL.