Spring Hill Manufacturing is a General Motors factory in Spring Hill, Tennessee. It opened in 1990 as the site for Saturn manufacturing and continued through March 2004 as the sole manufacturing plant overseen by the Saturn subsidiary. After the United Auto Workers ratified a new contract in March 2004, the plant became part of General Motors, but Saturn-only manufacturing lines continued until March 2007. The facility includes a four-cylinder engine assembly plant, auto assembly plant, paint and plastics plant, a Saturn parts warehouse, and a visitors center. In 2005, the plant had a yearly production of 198,142 vehicles.