The initial segment of the Link light rail line, currently under construction, is a 15.6-mile route that connects Downtown Seattle and Southeast Seattle with Seattle-Tacoma International Airport, making stops at 14 different stations. Once light rail begins running in 2009, it will run 20 hours per day, 7 days a week, carrying 30,000 people every day—a number that will continue to grow. In 2008, Sound Transit will break ground on University Link, a northward extension of light rail to the University of Washington, that will triple light rail ridership when it opens in 2016.

The 1.6-mile Tacoma Link light rail line opened in August of 2003 and connects the downtown Tacoma business, theater and university districts to the Tacoma Dome Station. From inception through the end of 2007, Tacoma Link has welcomed over 3.7 million riders.