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On September 25, 1920, the National Challenge Cup held a drawing for the first round of the 1921 National Challenge Cup. The drawing paired eighty-five entrants, down from 99 the previous year being due to the fact the entrance fee had been raised from $5 to $10. The cup a single elimination format consisting of six rounds and a single game final. The entrants were dividing into an eastern and a western division which led to a final pitting St. Louis Scullin Steel F.C. from the west and Brooklyn Robins Dry Dock from the east.
Booth, Joe (1920-09-27), "Graphs Draw Bye In National Soccer", The Bridgeport Telegram: 18
"BROOKLYN SOCCER TEAM WINS TITLE: Robins Dry Dock Beats Scullin Eleven of St. Louis, 4 to 2, for National Honors. PLAY EVEN IN FIRST HALF Defense of Westerners Weakens in Closing Period-A Bruising Battle on Fall River Field. Brooklyn Team Wins Toss. The Victory Clinched". The New York Times. No. 23, 097. April 20, 1921. p. 23.