Documentation/Guides
Parks and park factors | Baseball Data API
Parks and park factorsGrounds, their dates, and how they play.
/v1/parks lists every major-league ground with its first and last game; add season for the grounds used that year. /v1/parks/{id} gives, season by season, games, runs per game and the park factor: the home clubs' runs at the ground against their runs away, weighted by home games where clubs shared a ground.