The Cardinals were founded in 1898 in Chicago as an amateur team, the Morgan Athletic Club.
In 1901, owner Chris O'Brien acquired some used jerseys from the University of Chicago for the Normals.
The team was a charter member of the American Professional Football Association, forerunner of the NFL, in 1920.
The Cardinals and Chicago Bears are the only two charter members of the NFL still playing in the league today.
Through the heritage of the Morgan Athletic Club, the Cardinals also claim to be the oldest professional football team in the country.