The Pierce-Arrow Model 31 was a series of luxury cars introduced in 1919. The Model 31, which was also known as the Series 31, was the successor to the Pierce-Arrow Model 38. These cars were available in a range of open and closed body styles, and featured a 6.8L inline six engine generating 75hp. This power was sent to the rear wheels via a 4 speed manual transmission. Production of the Pierce-Arrow Model 31 lasted until 1920, when it was replaced by the Pierce-Arrow Model 32.