The Altamont Commuter Express (also known as ACE, pronounced "ace") is a commuter train service in California connecting Stockton with San Jose. It is named for the Altamont Pass, through which it travels. The service was started on October 19, 1998 with two trains daily in each direction, later increased to three trains in each direction, and as of August 2006 runs four trains daily in each direction, including a "midday" train each direction.