How Dense is Boulder?

People like to argue about how dense Boulder is, as if there’s a single answer. There isn’t. Depends on what you mean by “dense” 😉.

This came up at the recent TEDx Salon on Housing:

• Me: 74% of Boulder’s residentially zoned land is low-density.

• Mark: People always talk about low density, but Boulder is more dense than … (XYZ list of cities).

Who’s right? Technically, both of us. Annoying, I know 🤷. Here’s why:

Population Density (What Mark Meant)

Population density = total population / total land area. Easy math, important nuance.*

For Boulder:

• Population: 106,803

• Land Area: 26.55 sq mi

• Population Density: ~4,025 people/sq mi

How do we compare?

• Berkeley, CA: 11,917/sq mi

• Santa Monica, CA: 11,067/sq mi

• Alexandria, VA: 10,677/sq mi

• Santa Cruz, CA: 4,942/sq mi

• Tempe, AZ: 4,521/sq mi

• Ann Arbor, MI: 4,392/sq mi

• Boulder, CO: 4,025/sq mi

• Eugene, OR: 3,998/sq mi.

• Madison, WI: 3,391/sq mi

• Austin, TX: 3,007/ sq mi

• Fort Collins, CO: 2,969/ sq mi

• Chapel Hill, NC: 2,871/sq mi

• Gainesville, FL: 2,234/sq mi

Boulder is smack in the middle of this grouping, but that is because I made the list. Depending on where you draw the comparison list, you can make Boulder look dense or sprawled. Choose your own narrative.

Just for fun: San Sebastián, Spain (my favorite mid-sized city in the world) has nearly the same land area as Boulder (26.87 sq mi) and a population density of 7,766/sq mi.

Zoning Density (What I Meant)

Zoning density = how many dwelling units (DUs) per acre the city allows. This is the rulebook that determines what gets built.**

Let’s focus on Boulder’s residential zones (where 88.5% of the city’s homes are located). Boulder has many residential zones, but they can be categorized into three broad buckets:

• Low-Density (2–6 DUs per acre) - vast majority is single-family housing

  • Covers 74.33% of residential land

  • Delivers 43.92% of units in residential zones (38.87% of total DUs)

• Medium & Mixed Density (6–20 DUs per acre) - many single-family homes, plus single-unit attached homes and luxury townhomes

  • Covers 16.2% of residential land

  • Delivers 25.05% of residential DUs (22.16% of total DUs)

• High-Density (recently up to 28+ DUs per acre, but now an intensity standard) - condominiums and multifamily rental housing

  • Covers 9.49% of residential land

  • Delivers 31.03% of residential DUs (27.45% of total DUs)

Translation: high- and mixed-density zones punch way above their weight. They cover only a quarter of residential land but produce over half the homes.

Dan Parolek, author of Missing Middle Housing, recommends a more balanced breakdown: 50–60% low, 25–30% medium, 15–20% high.

What’s Next: My 2 cents

Should Boulder become denser? That’s a community conversation. But it’s worth noting that cities with higher density often support stronger small-business ecosystems, more vibrant arts and culture, and better public transit. We also know that building more housing within existing infrastructure helps protect agricultural land, reduces wildfire risk, and makes better use of limited resources like water.

With the new state Housing in Transit-Oriented Communities bill (HB23-1313) in motion, I’m not proposing major zoning changes in Boulder right now … I’d rather see how that plays out first.

But there are steps we can take now to help add workforce housing:

1. Identify City-Owned Land where we can build the kind of housing Boulder residents need, because the land cost will be stripped away. 

2. Reform the Development Process. Time to get rid of “growth control by hassle.” Talk to anyone who has tried to build housing or start a small business here, and they will describe the same experience: delays, ambiguity, endless reviews.

3. Address Second Homes & Speculative Buying. Second homes and speculative investors distort the market. Prices go up, year-round residents get squeezed out, and vacancy rises. We need smart policy here before things get worse.

4. More work on Accessory Dwelling Units (ADUs). Incremental, gentle densification that adds housing capacity within the existing neighborhoods while preserving established character. Despite the recent loosening of ADU regulations, they remain challenging for homeowners to build.

Still reading?? You’re a nerd. And now we’re in Dream Mode.

Dream Mode 1: What I’d Love to See

• Big, Bold thinking, like how to best use the Airport and Area 3 to support housing, parks, small businesses… mixed use.

• Neighborhood-scale density near connector road intersections, with walkable amenities and new housing types

• Intergenerational housing that matches students with seniors

Dream Mode 2: What I’d Love to See (But It Would Require Defying Capitalism and Colonialism)

Land Back. Some form of reparations. This city sits on stolen land … full stop. Our great-grandparents took it. And now we fight over who gets to “own” it and how dense it should be, as if we didn’t all inherit a crime scene. (I literally have a radio show on KGNU called Who Owns Boulder — the title kind of answers itself.)

But what if we gave some back? Not as a gesture. Not as a token. But as part of an actual long-term commitment to justice and stewardship.

We still have public land: Area III, the municipal airport, other scattered parcels. What if we got serious — like, radically serious — and partnered with Indigenous Tribes to return some of that land?

It’s not impossible. It’s just incompatible with everything we’ve built our housing system on so far.

*While Boulder’s planning department has its own population count, it is helpful to use Census data here when comparing Boulder to other cities

**I am using the spreadsheet in the image above, which reflects 2023 data (post-East Boulder Sub-Community Planning). This spreadsheet came directly from the Planning Department, but I categorized it and did the math. The city has since built more dwelling units, but, to my knowledge, has not rezoned.