Ballard Link Extension

The Ballard Link Extension is a planned light rail project to be built by Sound Transit in Seattle, Washington, United States. It would extend the 1 Line of the Link light rail system north by 7.7 miles (12.4 km) from Downtown Seattle to Ballard with intermediate stops in South Lake Union, Lower Queen Anne, and Interbay. The Ballard Link Extension is planned to serve eight new stations and rebuild portions of two existing stations. The project would comprise a new tunnel through Downtown Seattle and South Lake Union as well as elevated sections in other areas. It is planned to open in 2039, and has a projected total cost of over $20 billion.

The Ballard–Downtown Seattle corridor had been served by local streetcars and buses since 1890. Proposals to build rapid transit to Ballard date back to the early 20th century and were included in two unsuccessful ballot measures under the Forward Thrust program in 1968 and 1970. Sound Transit and the city government began a joint study of a potential light rail line on the corridor in 2013 that endorsed a route through Interbay. It was included as part of the Sound Transit 3 program, approved by voters in 2016, alongside an extension to West Seattle.

Environmental assessment for the combined West Seattle–Ballard project began in early 2018 and produced 24 early route options that would be among those studied in an environmental impact statement. The selection of a preferred alternative by Sound Transit was delayed due to opposition to a cut-and-cover station from residents in the Chinatown–International District neighborhood. Several design changes were made prior to the release of the draft environmental impact statement in 2022, which was followed by the selection of a preferred alternative for most sections; a decision for the Chinatown–International District neighborhood was deferred to a later date. A new route, which avoided construction of a station in the neighborhood's core, was selected as the preferred alternative in March 2023 but other options were retained for further studies. Due to delays in the planning process, the Ballard Link Extension was spun off into a standalone project in October 2023.