Bay Freeway (Seattle)

Bay Freeway
Mercer Street Connection
Route information
Length	0.7 mi[1] (1,100 m)
History	Canceled in 1972[2]
Major junctions
West end	SR 99 in Seattle
East end	I-5 in Seattle
Location
Country	United States
State	Washington
Highway system
State highways in Washington Interstate US State Scenic Pre-1964 1964 renumbering Former

The Bay Freeway, also referred to as the Mercer Street Connection, was a proposed elevated freeway in the South Lake Union neighborhood of Seattle, Washington. The 0.7-mile-long (1.1 km) freeway would have run parallel to a section of Mercer Street between Interstate 5 (I-5) and Aurora Avenue North at the Seattle Center.

Planning for the freeway began in 1954, with the proposal for a freeway from Elliott Bay to the Central Freeway, later I-5, via Broad and Mercer streets added to the city's comprehensive plan in 1957. Funded by a bond measure passed by Seattle voters in 1960, plans were drawn for the newly renamed Bay Freeway to serve a multi-purpose stadium at the Seattle Center via an elevated structure.

Citizen groups voiced their opposition to the project at public hearings in 1967, forcing the Seattle Engineering Department to consider other designs. After determining that a cut-and-cover tunnel would not be feasible, a second series of public hearings to discuss the impact of an elevated option were held in 1970, leading to widespread controversy and a civil suit launched in opposition to the freeway. The lawsuit ended in November 1971, with a King County Superior Court judge ruling that a major deviation from the voter-approved 1960 plan occurred, forcing a referendum to be held on whether to continue the project.

On February 8, 1972, the Bay Freeway project was rejected by a 10,000-vote margin in a municipal referendum, alongside the repeal of the R.H. Thomson Expressway. Mercer Street would later undergo several projects that attempted to provide congestion relief promised by the rejected freeway, culminating in the Mercer Corridor Project in 2012, which widened the street into a boulevard.