It was the first low-floor light rail vehicle to be used in the United States.

[5][6] It first entered service in 1997 with its only operator, TriMet, on the MAX light rail system in Portland, Oregon, United States.

It was the first order for low-floor light rail vehicles (LRVs) in North America.

[10] TriMet later purchased 27 more SD660s (initially 17 cars, with another 10 added to the order in 2002),[11] which were built between 2003 and 2005.

[14] Other Siemens light rail vehicles for the American market: