I n the early 20th century, the heavy industrial development in the Lake Union area led to a high demand for labor. In response, residential growth near the lake expanded alongside industry. Although many new single- and multi-family units were built during this time, workers still had to look for additional dwellings, and they began to use houseboats for temporary shelter. Also, public amenities, including the Washington Park Arboretum and the Montlake Playfield, were build during this time to accommodate the growing population.
Through the 1930s and 1940s, residential development slowed due to the effects of the Great Depression, and because of World War II, which drew attention and resources away from domestic building and construction. This all began to change in 1940, when the Lacey V. Murrow Bridge was completed to the south between Mercer Island and Seattle, which spawned tremendous growth on the Eastside.