According to this recent report by Smart Growth America, which looked at "walkable urbanism" in the largest 35 metro areas in the US, only about 1.2% of land is, on average, built out in this way. Everything else needs to be driven.

But here's the thing. Humans seem to really enjoy walkable urbanism, and will usually pay more for it:

City dwellers will pay to live in a walkable location. Real estate in these areas averages a 34% price premium per square foot in for-sale housing and 41% for multifamily rental apartments.

It also, by definition, punches above its weight:

Walkable neighborhoods in just those 35 metro areas account for 19.1% of the total US real GDP and 6.8% of the total US population, by the researchers’ calculations.

That's how density works. You get to do more, with less.

At the same time, not every place should be Midtown Manhattan (which the report labels as the highest walkable urban place with a floor area ratio of 40). There are a wide range of densities that will work, including modest ones (FARs between 1-3).

Here in Toronto, many of our single-family home neighborhoods have densities that are zoned for a maximum FAR of 0.6, which is quite restrictive if you're hoping to build something like a multi-unit building.

This is, of course, the point. But imagine what all could be done here with even an incremental change.