The Washington state Senate passed legislation Tuesday that would allow duplexes or fourplexes in most neighborhoods in most cities throughout the state, regardless of local zoning rules that have long limited huge swaths of cities to only single-family homes. House Bill 1110, which passed on a bipartisan 35-14 vote, aims to increase housing supply and density by allowing more homes on plots of land that have traditionally allowed only one. Increasing housing supply, supporters say, is critical to combating a housing crisis that’s brought escalating home prices and homelessness numbers throughout the state.