Sound Transit’s Link light rail turned three amid continued steady ridership growth since opening day. Link has carried an estimated 21.6 million riders since it opened July 18, 2009.

The latest second quarter ridership numbers for 2012 show link up 10% over the second quarter in 2011. Link carried an estimated 2.19 million riders in the second quarter of 2012 compared to 1.98 million in 2011.

Link currently carries about 28,000 riders each weekday.

Link light rail ridership continues to grow faster than national averages for other systems. Nationally, light rail (modern streetcars, trolleys and heritage trolleys) ridership increased 6.7% in the first quarter of 2012, according to the American Public Transportation Association.

The Central Link line is the first portion of what will be more than 50 miles of light rail serving the Central Puget Sound Region. University Link, a 3.1-mile underground extension from downtown Seattle north to Capitol Hill and the University of Washington is under construction and will open in 2016 along with an extension south of SeaTac/Airport Station to S. 200th Street.

In August Sound Transit will break ground on a 4.3-mile extension from the University of Washington to Northgate in Seattle scheduled to open in 2021.

Voters have also approved extensions to Bellevue, Redmond, Mercer Island and the Federal Way area scheduled to open by 2023.