A tidal shift is happening in American zoning, long one of the stodgiest corners of the local lawbook. These changes will have major impacts on housing affordability and sustainability. And the first big wave carried by this tide has arrived, appropriately enough, in the coastal state of Oregon.

This wave goes by the name HB 2001. It’s statewide legislation that passed the Oregon Senate, arguably its biggest hurdle, on the last day of June. If it’s signed into law — as expected — by Gov. Kate Brown, it will loosen the zoning stranglehold that most cities have put on housing choice. Combined with renter protections also passed in the state this year, it puts Oregon, a leader in statewide land-use planning since the 1970s, at the forefront nationally in taking an ambitious and comprehensive approach to addressing the housing crisis.

Zoning rules say what sort of activity can go where — and, much more so, what sort of activities can’t. For nearly a century, zoning imposed at the behest of and for the benefit of the wealthy has prioritized detached single-family houses above all other forms of housing — indeed, above all other land uses. So strongly has this one use been favored that in Boulder, as in many other cities, at least 75% of the residential land area is restricted to single-family housing.

This has been great for those both rich enough to buy houses and not excluded by red-lining or implicit discrimination (a widespread scourge to which Boulder was not immune). But it has terribly penalized everyone else. Its consequences include fewer homes at higher prices, racial segregation, sprawl eating up cornfields and prairies, and much, much more driving. It has resulted in inefficient use of land and vast landscapes of detached houses that take inordinate amounts of energy to build, to heat and cool, and to fill with stuff.

HB 2001 upends this longstanding paradigm, expanding housing choice by allowing duplexes, triplexes, fourplexes, or “cottage clusters” on every lot currently restricted to single-family houses in cities over 25,000 people. Single-family housing is still allowed in these areas, but it’s no longer the only option. HB 2001 opens up the possibility of new housing types that heretofore have been largely foreclosed. As Tina Kotek, House speaker and the main force behind the bill, said on NPR: “This is about choice. This is about the future, this is about allowing for different opportunities in neighborhoods that are currently extremely limited.”

While this is the first statewide move to upend single-family zoning, it’s part of a larger shift towards loosening the zoning straitjacket. Minneapolis also did away with single-family zoning earlier this year, and the trend is clear across the country — mostly in progressive strongholds — as cities and towns large and small have allowed more “backyard cottage” ADUs, removed prohibitions on “missing middle” housing types, like duplexes, and adopted form-based codes that prescribe the appearance of buildings but not their use.

And at the federal level, at least three progressive Democratic candidates for president — Sens. Elizabeth Warren and Cory Booker, and Julian Castro — have proposed policies that would prod cities with overly restrictive zoning to loosen their rules. Like progressives at the state and local level, these candidates understand that exclusionary zoning benefits the well-off but harms the disadvantaged. They also see the environmental costs of our national love affair with single-family zoning, and how it impedes progress towards ambitious climate goals.

Oregon lawmakers felt compelled to act after municipalities in the state, too beholden to well-off homeowners, failed to adequately address the housing crisis. Colorado cities are similarly remiss.

So, congratulations to Oregon for leading the return to more just, equitable and sustainable zoning, and for combining that with sensible renter protections. Colorado’s housing crisis is every bit as dire as Oregon’s, with prices rising faster than wages, diminished housing security, inadequate supply in booming regions, and growing homelessness. It’s time for us to follow Oregon’s lead.

We may not have an ocean, but we can still create a wave.

Kurt Nordback lives in Boulder.