This guest post is by Michael Andersen of Portland Afoot, PDX's 10-minute newsmagazine about buses, bikes and low-car life.

If Portland successfully builds a city of 20-minute neighborhoods, it'll do more than just make us all happier, healthier and safer.

It'll make middle-class consumers walk more. It'll kill auto-oriented businesses that don't adapt – and create opportunities for entrepreneurs who do.

In this third post of my series for WPC about the pedestrianization of Portland retail, let's think about what successful sidewalk-oriented businesses might look like.

Here's what I think: They'll look like food carts.

Food carts, which cluster into pods that function as the food courts of Portland's Transit Mall, are the signs of a city that's shifting away from automobiles – and not just because they're usually located on a former parking space. They require a vibrant sidewalk culture (to turn a profit, a cart pod needs about 75 to 100 passers-by per cart per day) but their low-overhead business model lets them survive on a fraction of the sales volume of, say, a McDonalds (1,400 visits per weekday).

Unlike strip malls and big-box stores, a successful food cart doesn't need to lure patrons from miles away. It just needs to lure in the neighborhood.

I stole this insight from my colleague Chris Smith, a Portland planning commissioner and one of Portland's savviest transportation thinkers. In the first post of an insightful trilogy about what makes food carts work, Smith asked a fascinating question:

"How many of the essential services for a neighborhood could be delivered via a cart?"

A tobacco shop? A farmer's market? A tool library? A pharmacy? A copy shop … or, ten years from now, a 3-D printing station?

A bar?

At the time, I wrote in a comment to Chris that neighborhood watering holes, the anchor of most 20-minute neighborhoods, would never get past zoning boards. Oops. As Portland's consumer habits shift along with its commuting habits over the next 30 years, here's to many more pleasant, profit-generating surprises to come.

The April issue of Portland Afoot's 10-minute newsmagazine ranks the metro area's best employers for low-car commuters. WPC supporters can subscribe for $10 a year with coupon code WPCWALKS.

Creative Commons food cart photo by Flickr user Johnjoh.