The Cincinnati Red Stockings lost in regular season play to defending champion Brooklyn Atlantic, so was not able to claim the championship Mutual of New York was leading, 13–12, in the deciding game of its series with the Chicago White Stockings when Mutual left the field in protest. Officials decided to revert the score to the end of the last completed inning and awarded the game, and thus the championship, to Chicago Dozens of amateur teams, although members of the association, are omitted here. Standings were now determined by winning percentage, rather than by number of total wins, as in years past. Historical records of game results and player statistics may be missing or incomplete. Union and Atlantic clubs played one tie game.
1870 Cincinnati Red Stockings LogoCincinnati 276.809-
1870 Chicago White Stockings LogoChicago   227.7593.0
1870 Philadelphia Athletic LogoAthletic 2611.6973.0
1870 New York Mutual LogoMutual 2915.6493.5
1870 Brooklyn Atlantic LogoAtlantic 2016.5568.5
1870 Lansingburgh Union LogoLansingburgh 1113.46011.5
1870 Rockford Forest City LogoRockford 1013.43812.0
1870 Cleveland Forest City LogoCleveland 915.37513.5
1870 Washington Olympic LogoOlympic 1018.35714.5
1870 Morrisania Union LogoUnion 718.28016.0
1870 Washington National LogoWashington 29.18214.0
1870 Brooklyn Eckford LogoEckford 212.16715.5
1870 Baltimore Marylands LogoBaltimore 214.12516.5
1870 Boston Tri-Mountain LogoBoston 04.00012.5
1870 Portsmouth Riverside LogoPortsmouth 06.00013.5
1870 Milwaukee Cream Citys LogoMilwaukee 00.000-