Within the downtown area (the city center) is the Portland Transit Mall, a transit-priority corridor on which buses and light rail trains from many different parts of the region converge. First opened in 1977, and for three decades served only by buses, the transit mall underwent major changes in 2009. Tracks for light rail (MAX) were added, bus stops spaced farther apart, and the left lane opened to general traffic (but with right turns prohibited). To facilitate this major renovation and rebuilding, lasting more than two years, all bus routes using the mall were diverted to other streets (mainly 3rd and 4th avenues) starting in January 2007. The transit mall reopened to buses on May 24, 2009, and operator training runs on the new light-rail tracks took place during the late spring and summer. Light rail service on the transit mall was introduced on August 30, 2009, when the MAX Yellow Line moved to the mall from its previous routing. The new MAX Green Line opened 13 days later, on September 12, and it also serves the downtown transit mall.