Pete Alonso hit his 40th home run of the season this afternoon in Kansas City, and now owns the record for most home runs by a National League rookie. Alonso surpasses Cody Bellinger, whose record of 39 was set in 2017. Bellinger set the record on September 22; Alonso set his on August 18.
Before Bellinger, the record was shared by Frank Robinson’s 38 home runs in 1956 for the Reds, and Wally Berger in 1930 for the Boston Braves. The all-time rookie record was set just last year by Aaron Judge of the Yankees with 52.