Trading lower rent costs for higher transportation costs is a recipe for traffic jams—not affordability. Bozeman needs more quality, affordable housing, but not all cheap housing is affordable. Ringfencing the city with high-density, low-cost housing perpetuates car-dependency and results in those living far from jobs and services spending more of their paychecks on car payments and greater traffic congestion.

The city’s recent housing needs assessment finds that since 2010 housing prices have gone up four times faster than wages (prices for homes have increased by 75 percent since 2012) and that some 6,000 new housing units are needed by 2025. Affordability challenges our community on many levels, not least by threatening to price out many who contribute immeasurably to the thriving and vibrant city we share and love.

After housing, the next largest expense for most households is transportation. The average Gallatin County household owns more than two cars. AAA estimates that owning a vehicle, on average, costs $8,500 per year (over $700 per month). It follows that a $1,500-per-month apartment where two people can share one car is more affordable than a $1,000-per-month apartment requiring two cars.

While few Bozeman households are likely to go car-free altogether, greater accessibility allows for owning fewer cars. U.S. Census data shows that households near Bozeman’s core, on average, own 0.5 fewer vehicles than those on the city periphery. Households near the university, on average, own 0.4 fewer vehicles still. These transportation cost savings translate directly to more money to spend on other necessities.

Compounding the affordability challenge, building and maintaining new roads drives up housing prices. Most of the city’s budget for building and maintaining streets comes directly from property owners or buyers. Since 2010, annual Bozeman tax assessments for streets have increased from $2.1 million to $7.5 million, amounting to an increase of about $250 in annual property tax assessments per household. The city also collects $3–$7 million each year in street impact fees from new developments—fees which, in turn, get passed on to buyers of new homes.

Building “in” where residents can walk, bike, or take transit to work, child-care, or a grocery store requires fewer vehicles and roads than building “out.” Modifying our city code to allow more invisible density (e.g. dividing existing single-family homes into multiple units), hidden density (ADUs or mother-in-law suites), and gentle density (e.g. rowhouses) can help meet our housing needs, in the right places, without undermining community character or paving over wheat fields.

Faced with similar affordability challenges, other cities and states are removing barriers to these forms of density. In Washington state, lawmakers are currently considering a bill that would allow two ADUs per lot while reducing setback, height, and size limits. The city of Minneapolis just adopted a plan to create more infill housing near jobs and services by allowing duplexes and triplexes across the city and eliminating off-street parking requirements. Bozeman could do the same.

Building housing on the city’s periphery is expedient—greenfield development offers lower-cost land and fewer objecting neighbors—but is not the best approach for meeting Bozeman’s affordability needs. As the city develops its new growth plan, it should consider adopting policies that support the development of affordable housing that is proximate to jobs and services, especially in the forms of invisible, hidden, or gentle density. Building “in” demands greater political will, but is a superior recipe for creating actual affordability.

Mark Egge is a Bozeman-based transportation planning consultant.