Why do the Detroit Lions play on Thanksgiving?

The Detroit Lions play on Thanksgiving due to a tradition that began in 1934 when George A. Richards moved the Portsmouth Spartans to Detroit and renamed them the Lions. Richards scheduled a Thanksgiving game and secured a national radio broadcast, making it the first NFL game to be broadcast nationwide. This association between the Lions and Thanksgiving became a lasting tradition, with the team playing nearly every Thanksgiving since, except during World War II.