The Bothell–Everett Highway (State Route 527) remained a two-lane rural highway through Mill Creek until the start of an expansion and improvement program in the 1990s. It was widened to four lanes with a center turn lane, and also gained bicycle lanes, sidewalks, and new landscaping features. The section through Mill Creek, from 164th Street to 132nd Street, was completed in 2006 and required the construction of retaining walls and detention ponds due to the limited space for the road. The project also included new bus stops that were later upgraded with the opening of the Swift Green Line bus rapid transit system in March 2019.