California’s past and future collided in this week.

That’s not how any of the participants in a raucous, three-city meeting on the Peninsula described it. But as we have reported, the gathering vividly illustrated the growing gulf between those embracing a more urban and efficient model for housing, in this case East Palo Alto, and those like Palo Alto and Menlo Park who remain wedded to the old single-family suburban ideal.

The flashpoint between them was SB50, the landmark piece of housing production legislation now inching its way through the Sacramento political meat grinder. If it emerges relatively intact, it could push multi-family housing into urban and suburban communities across the state, permanently altering our failed status quo.

And that, Palo Alto and Menlo Park residents explained this week, is what concerns them: Being forced to accept new, denser, less expensive housing into their neighborhoods might bring with it less affluent neighbors. They have benefited directly from years of increasing economic exclusion in their communities, and they want to keep it that way.

It’s not an attitude that’s limited to Menlo Park and Palo Alto, of course. It can be found in other upscale communities that grew up on the fringes of California’s cities during the great suburban expansion. In the three decades following World War II, the state added 3.5 million homes, mostly in places where 70 percent of the land was restricted solely to single-family construction.

Those low-density suburbs answered the needs of the 1960s and ‘70s as millions of residents streamed into a state where land seemed virtually limitless.

But we should all agree that it’s not a feasible blueprint as California heads toward the middle of the 21st Century.

To start with, there’s just too many of us: Even as today’s housing crisis pushes thousands of families out of the state, California’s population has doubled since 1970 and is projected to keep growing.

Since then, we have learned to tally the true costs of drive-to-everywhere suburban sprawl: Environmentally, economically and in reduced quality of life. Meanwhile, generational inequality between the housing “haves”and “have-nots” continues to metastasize.

Densifying our existing communities is the only way we can address these issues, going upward rather than outward. Well established, well located communities already stitched into our regional fabric — cities, in other words, like Menlo Park and Palo Alto — are in fact well placed to help lead us into the future. If only they could get over their infatuation with the past.