On May 24, 1935 the Cincinnati Reds beat the Philadelphia Phillies 2-1 at Crosley Field in the first night game ever played by Major League Baseball teams.
It should be noted that artificial lights date back as far as the 1880s and were used in minor league ball in the 1920s. The Kansas City Monarchs of the Negro Leagues also played night games as early as 1930, carrying around portable lights on their bus.
The idea seems to have caught on.
(Cross-posted at Lippmann's Ghost.)