Jefferson Street Grounds was a baseball field located in Philadelphia. It was also known as Jefferson Park and Athletics Park. It was home to the Athletic Club of Philadelphia from 1871 to 1876, five seasons in the National Association and one in the National League of Base Ball Clubs. From 1873 to 1875, the Athletics shared it with the Philadelphia Base Ball Club, also in the National Association. Later it was home to the American Association Athletics beginning 1883, moving in from Oakdale Park, until 1890. The grounds were located on a large block bounded by Jefferson Street ; 25th Street ; Master Street ; and 27th Street. Although typically listed as one ballpark, the 1870s diamond was located in the opposite corner of the block from the 1880s diamond. The facility opened to professional league baseball on May 15, 1871. The seating capacity was meager, only 5,000 seats. The inaugural National League game was played there, on Saturday, April 22, 1876, between Athletic and Boston; the Bostons won 6-5. By a quirk of fate, it was the only NL game played that day, all others being rained out. This game is often pointed to as the beginning of Major League Baseball. Baseball had first been played on the site in 1864. Several local clubs held their games there, including the historic Olympic club which had begun playing various varieties of ball starting in the early 1830s and had adopted the "New York game" by 1860. When they began playing at the Jefferson site, the diamond was situated at the southeast corner, at 25th and Master. The Olympics built a clubhouse along Master. Jefferson was behind right field. Local newspapers typically gave the ballfield location as "25th and Jefferson". After the Athletics were expelled from the National League following the 1876 season, the field fell into disuse. The city cut 26th Street through, allowing the eastern half of the large block to be developed. The western half remained vacant. The new American Association team decided to move from Oakdale Park after their inaugural 1882 season. The club leased the western half of the Jefferson lot and put a new diamond and stands at the northwest corner. Local newspapers then referred to the ballfield location as "26th and Jefferson", where there was an entrance gate. Also by this time the venue was being called Athletic Grounds or Athletic Park. The last major league game played in the park was October 11, 1890, but the ball field still exists in a revised form. The ballpark site is currently occupied by various structures including Daniel Boone Public School aka Camelot Academy at 1435 N 26th St, and the Athletic Recreation Center and its ball fields. The field at the northwest corner of the lot approximates the location of the 1883-1890 diamond.
