Manufactured housing is the largest source of unsubsidized affordable housing in the United States, providing homes to roughly 7 million families. Since 2024, at least five states have passed laws requiring cities to allow manufactured housing wherever traditional site-built homes are permitted, joining 19 states with similar laws already on the books. But these laws appear to have made little difference. After controlling for income, population density, and climate, states with these laws have about the same manufactured housing shares as those without. Even the most receptive states exceed predictions by only 2-3 percentage points. Expanding manufactured housing will require more than legislation: enforcement and federal action on financing barriers are likely both necessary.