Today marks ten years since the opening of the Seattle light rail transit system. I was one of the 45,000 riders that boarded the light rail train for the first time, on July 18, 2009.
The initial line ran from downtown to Tukwila International Boulevard (close to Seattle-Tacoma airport). Four more stops have opened since then (Seattle-Tacoma airport & Angle Lake to the south, Capitol Hill and University of Washington to the north). The next extension of three more stops to the north, will open in 2021.

The initial line ran from Westlake station in downtown Seattle to Tukwila International Boulevard station. SeaTac/Airport station opened five months later in December, 2009.
Thanks for the correction.
I had forgotten that the line first ran to Tukwila only!
I corrected the text in the blog post.