Housing in America’s fast-growing cities has become increasingly unaffordable because elected officials let it get that way. They’ve caved to the not-in-my-backyard contingent, blocking compact development and foisting expensive mandates like parking requirements on new buildings. With population growth outpacing the growth of housing, living in neighborhoods with convenient access to jobs, schools, or even a grocery store becomes less attainable for more people.

A city like Denver, where people are migrating every day, needs more walkable development in its neighborhoods if it’s going to stay affordable. But NIMBY pressure makes this type of growth politically difficult. The classic NIMBY stance says new people moving to the city are fine, they just don’t want people moving to “their” street. They don’t want “their” view altered by new development, or someone else occupying “their” free on-street parking spaces.

The result is unaffordable neighborhoods for everyone.

Enter the “yes in my backyard” movement. YIMBYism is gaining steam — especially in Colorado, thanks in part to the defeat of a Boulder ballot measure that would have dramatically curtailed development. Building off that momentum, Better Boulder hosted the first annual YIMBY conference just up U.S. 36 last weekend. About 150 people convened to share ideas and political strategies to promote housing policies that will allow everyone who wants to live in cities to live in them.

“I really want everyone to come away from this very motivated and with the understanding of how accessible local politics is,” said keynote speaker Sonja Trauss, who founded the San Francisco Bay Area Renters Association (SFBARF). Trauss began organizing pro-development renters in 2013 after seeing a sign in a San Francisco neighborhood that read, “Grow Potrero responsibly.”

“As everybody knows, that means don’t grow it,” Trauss said. “It was in response to a 300-unit project in that neighborhood. As usual I was disgusted. In the face of the Bay Area’s severe housing crisis, I was always shocked when people were against building new housing.”

Like the Bay Area, Denver’s population is growing fast — much faster than the creation of new places to live. The shortage of housing propels rents and home prices upward, forcing people to live in the less expensive sprawl outside the city, further away from walkable, bikeable, and transit-rich neighborhoods.

Not only is this pattern a disaster for housing, it’s terrible for streets and transportation. People’s transportation costs rise as they move away from the city center in search of affordable rents. It also causes more traffic, as people living farther out have little choice but to drive into the city, where the jobs are. It’s not sustainable.

NIMBYism is alive and well in Denver. Some residents of Curtis Park, for example, oppose new apartments because the developer isn’t building any parking. Current residents fear losing the ability to store their private vehicles on a public street, right in front of their homes, which they see as a right. (As one YIMBY presenter said, quoting Donald Shoup, “Parking requirements are a fertility drug for cars.”) Even a small, three-story apartment building met with intense opposition from residents of Crestmoor Park and a scolding in the Denver Post (headline: “It’s time to take our city back, Denver“).

The idea that development is inherently bad, or that “our city” can only be a collection of single-family homes, is a common reaction to growth, says Anna Fahey of Sightline Institute, a Seattle think tank that researches urban housing policy.

“Growth feels big and scary, and leaves people feeling defensive about their own self interests and about their turf and what they have on the chopping block, rather than sparking a civic dialogue about how the community can benefit,” Fahey said.

Sightline supports Seattle Mayor Ed Murray’s plan to allow the development of compact housing, especially near transit, where previously only single-family homes were allowed. The plan opens the door for 50,000 new housing units, 20,000 of which would be priced below market rate. Murray faced opposition from people who would rather maintain the sprawling status quo than embark on a clear path to solving Seattle’s housing shortage.

“Growth is very abstract,” Fahey said. “The way that we’re talking about it a lot in Seattle seems to be about this faceless army gathering its troops at the walls of the city. It’s not stories of people having children in Seattle; it’s not stories about people moving back after being at college or people like your neighbor who came for an excellent job opportunity… these are human stories and we can forget that in the way that we talk about growth.”

The YIMBY conference was all about mobilizing at your local city hall or planning commission, organizing for policies that make cities open to everyone, not just the people who can afford it.

“We absolutely have to get better at shifting the conversation from the character of the built environment to the characters who make up our community,” Fahey said. “We have to shift from talking about whether the buildings are ugly or too high or not built to last… to really what makes up the soul of our city. Or else we shut a bunch of people out.”

If you couldn’t make the conference, the organizers put together this quick video about the proceedings:

An earlier version of this article erroneously stated that the article entitled “It’s time to take our city back, Denver” was written by the Denver Post editorial board. It was in fact commentary written by a Denver resident.