Construction of the light-rail system began in 1990. The project took advantage of miles of unused rail bed and railroad right-of-ways that were expandable, as well as an unused rail deck on the Eads Bridge and tunnels under the downtown Central Business District.
Three years later, on July 31, 1993, MetroLink debuted with a three-day, fare-free introduction to the St. Louis region. Everyone had an opportunity to take a ride on the first light-rail system in the St. Louis region, connecting 16 stations over 14 miles from St. Louis County in Missouri to St. Clair County in Illinois. More than 180,000 rode MetroLink during the three-day introduction and by Labor Day, only a month after beginning regular service, the one-millionth passenger boarded MetroLink.
MetroLink expanded service to Lambert Airport in 1994, as well as to the new East Riverfront MetroLink Station. MetroLink added another station at Lambert Airport to the East Terminal (now known as Terminal #2) in 1998.
The success of MetroLink was seen in more than climbing ridership numbers. MetroLink's contribution to regional economic development became evident through significant investments made in areas near MetroLink. Since 1993, more than $2 billion in development has occurred near MetroLink.
The popularity of the initial MetroLink alignment prompted discussions for expansion further into Illinois. This led to the development of the St. Clair MetroLink extension, and construction of the new line began in 1998.