An 1889 fire that claimed over twenty-five city blocks, every wharf and mill from Union to Jackson Streets, and one million rats, spurred Seattle to ban wooden buildings in the business district downtown. The decree caused a land rush to the closest source of clay, at the southwest corner of Lake Union. Excavation of Queen Anne Hill to make clay bricks transformed the southern slope of the hill, originally steeply angled down to the lake. In 1911, Mayor Hiram Gill proposed to blast Queen Anne Hill into the lake with high-pressure water. He wanted to fill in Lake Union in order to create a flat plain for commercial expansion. The citizens felt they had lost enough hills, and wisely voted down Gill’s vision.