Last week we looked at how cities’ choices about the allocation of street space can have an impact on equity. Another area of interest worth exploring in that realm is the idea of “location affordability.”

The topic of housing affordability has come up a lot this campaign season, but there’s a compelling case that it’s really a mistake to talk about housing costs in isolation.

You’ve heard the expression “drive ’til you qualify.” The idea is that if you can’t afford a house near your job or some nice amenity, then you should look farther afield because the housing will get progressively cheaper the greater distance you go.

At some point though, you’re also going to spend more time and money on transportation the farther out you get, so on some margin it makes sense to pay a bit more for housing in order to save on transportation.

As Wonkblog’s Emily Badger wrote, the Center for Neighborhood Technology’s H+T Index shows you roughly where that line is in different regions of the United States, and they have an interactive map that allows you to view the location affordability ranking for your neighborhood.

The standard definition of housing affordability says affordable housing should cost 30% of the area median income or less. CNT says transportation should cost no more than 15%, so an affordable location would be a place where your combined housing and transportation costs add up to no more than 45% of income.

In my neighborhood in Bella Vista, housing costs are about 33% of area income, so a bit pricier than what’s considered affordable, but transportation costs are around 10%, so total H+T costs add up to 43% of area income.

They also compile data on many other factors relevant to housing and transportation affordability, and you can play with the maps and look at the H+T profiles for Census block groups, tracts, municipalities, counties, CBSAs, MPOs, and Congressional districts.