Colorado’s population has officially topped 6 million, according to the Census Bureau’s latest state population estimates. But the bigger story is what’s happening underneath that milestone: population growth is slowing sharply. A state long associated with a boom is now growing at a rate Colorado hasn’t seen since 1989.
Population growth is a vivid story told through moving trucks, change of address forms, births, and deaths—but what if it’s the wrong statistic to focus on?
Imagine it’s 2040, and Colorado’s population is exactly the same as it is today. No in-migration from other states or countries. No headline growth. Just a steady equalizing flow of births and deaths.
But life doesn’t stand still. Households change shape, couples split up, kids leave home, spouses pass away. More people live alone, for longer. By 2040, the oldest Millennials will be just a few years from Medicare eligibility—an age when household sizes often shrink. According to the State Demography Office, household size has been on a steady decline from 2.56 in 2010 to 2.43 in 2025; forecasting ahead to 2040, it could be down to 2.38 people per household. So even with zero population growth, Colorado will still add households—a lot of them.
By 2040, that shift alone would mean more than 51,000 new households, and therefore demand for 51,000 additional homes. That’s roughly 3,400 new units every year just to keep up with changing household patterns—and that’s before you account for the backlog. Colorado has already been underbuilding for years: an underproduction that the State Demography Office (using the same approach ECO developed for DRCOG and Up for Growth) estimates has left the state about 106,000 homes short.
Put the two together:
- 51,000 homes to meet new household formation (with no population growth)
- +106,000 homes to close the existing deficit
- = 157,000 homes needed, even if Colorado doesn’t grow by a single person
The point isn’t just forecasting—it’s knowing who’s here today and what they might need and want tomorrow. If we wait for population growth to “prove” we need housing, we’ll always be behind. A resilient housing market is what keeps Colorado affordable, keeps employers hiring, and keeps the state attractive when the next wave of in-migration arrives.