- National Association of Amateur Base Ball Players: Star of Brooklyn, 30-13
- National Association of Junior Base Ball Players: Fly Aways
The tenth founding member, the
National Club Of Washington , did not enter a team for the championship until
1872 .
- Ross Barnes of the Boston Red Stockings finishes in the top 5 in 11 different offensive categories. He leads the NA in runs scored, total bases and times on base. He is second in on-base percentage, doubles, triples and walks. He finishes third in batting average (.401) and hits. He places 4th in slugging percentage and 5th in runs batted in.
- Rynie Wolters of the New York Mutuals leads the league in games started, complete games, and innings pitched and ties for the league lead with 1 shutout. He also leads the NA with 44 RBI while batting .370.
- May 4 - The National Association begins play at Hamilton Field in Fort Wayne , Indiana , with Forest City Of Cleveland visiting the Kekiongas Of Fort Wayne . Fort Wayne wins 2-0 behind the pitching of Bobby Mathews , the lowest scoring game of the season. Deacon White gets the first hit. Joe McDermott, who will only have 11 career hits and 4 career runs batted in, drives in the first run in professional baseball history with a single in the 2nd inning, scoring Bill Lennon . Ironically, neither McDermott, Lennon, nor even the Kekiongas would finish the season
- May 6 - Cap Anson makes his professional debut with the Rockford Forest Citys .
- May 8 - Ezra Sutton of the Cleveland Forest Citys hits the first home run in professional baseball history in the 4th inning against the Chicago White Stockings . For good measure, Sutton adds a second home run in the 7th inning, but Cleveland falls to the White Stockings 14-12.
- May 20 - In Boston , Mort Rogers introduces a scorecard with a picture of Harry Wright on the front. Each Red Stockings home game would feature a different player so that spectators could collect them and have a full set of Red Stockings players by season's end. This marketing strategy would be used throughout the 19th century and would ultimately evolve into Tobacco Cards and, eventually, Baseball Cards .
- May 25 - Lip Pike of the Troy Haymakers collects 6 hits in a 25-10 victory over the New York Mutuals .
- June 19 - The Fort Wayne Kekiongas , leading the Troy Haymakers 6-3 after 6 innings at Troy, refuse to allow another ball to be used after the game ball becomes ripped because of the reputation of the Haymakers using illegal balls in the past. The umpire (Isaac Leroy or Ed Tighe depending on the source), after 5 full minutes of ordering Fort Wayne back on the field, calls the game a 9-0 forfeit in favor of the Haymakers.
- June 27 - In an era of high scoring games being the norm, the Philadelphia Athletics defeat the Troy Haymakers by the amazing score of 49-33. Both pitchers go the distance in the 4 hour slugfest in which both teams score in every at-bat.
None
- Wright, Marshall (2000). ''The National Association of Base Ball Players, 1857-1870''. Jefferson, NC: McFarland & Co. ISBN 0-7864-0779-4 (Postlude, p328-29)
- Ryczek, William J. (1992). ''Blackguards and Red Stockings; A History of Baseball's National Association 1871-1875''. Wallingford, CT: Colebrook Press ISBN 0-9673718-0-5
- Orem, Preston D. (1961). ''Baseball (1845-1881) From the Newspaper Accounts''. Altadena, CA: Self-published. ISBN-Unknown
- Charlton, James (1991). ''The Baseball Chronology''. New York: Macmillan ISBN 0-02-523971-6
