The great majority of development in American cities over the last 75 years has been single-use, with neighborhoods of exclusively single-family houses separated from nearby commercial strips with big parking lots along wide roads.
The downtown/center of older cities may still have mixed use, and there have been changes happening in recent years to allow/build more apartments and mixed use areas, but, generally outside of the densest parts of the largest cities commercial and residential areas are required to be separate, with personal cars as the primary/only way to get between them.
This has been a bit of a self-reinforcing phenomenon, IMO, as car-first infrastructure puts people at the mercy of traffic congestion, and means that any apartment building or business in their vicinity will result in more cars passing through, more congestion, more competition for parking, as well as the presence of the large parking lots that cities mandate for any new construction, which themselves make it unpleasant to get around in any other way.
> the median distance to the nearest food store for the overall U.S. population was 0.9 miles, with 40 percent of the U.S. population living more than 1 mile from a food store. The median distance to the third-nearest food store for the overall population was 1.7 miles. When the ERS researchers looked at rural food store access, they found that the median distance to the nearest and the third-nearest food store was 3.1 miles and 6.1 miles, respectively.
In older areas, some. But practically anything after WW2, not nearly as much.
It's somewhat misleading to talk about distance-to-X in a lot of American places. I live less than a mile from the nearest grocery as the crow flies, but if I wanted to walk there I have to traverse my entire street to get to an exit road (as opposed to walking out my back gate; the whole back is fenced because the exit road is directly behind my house). Then I have to walk down a fairly busy one-lane-each-way road with no sidewalks or shoulders present (i.e., you're going to be walking in a shallow drainage ditch - hope it's not raining!) for a few hundred meters, cross two busy multilane roads, and walk across an unshaded parking lot.
