US "missing middle" zoning reform goes mainstream, led in part by Republican states

"Missing middle" housing (duplexes, triplexes, ADUs) is going mainstream on 2026 US city/county agendas. Idaho's HB 1001 and SB 1352 cap parking and minimum-lot-size rules and permit gentle density by right; there is genuine bipartisan local resistance to state preemption of council zoning powers.

A property-rights-based, supply-side route to density that doesn't read as left-wing — useful for UK "gentle density" and "street votes" debates, and the preemption fight mirrors UK national-target-vs-local-control tensions.