There are lots of ways. Extremely high gasoline taxes seem to be popular in Europe. When driving costs $10 or $12 a gallon instead of $2 or 3, people want to drive a lot less.

High property values also work, as in Europe. In a relatively small European country, there is just a lot less land supply, so it costs a lot and people tend to build much more densely. By contrast the US is huge and has an enormous amount of vacant land, so land is (relatively) extremely cheap in the US, encouraging low density development.

Finally, the main reason low density is tenable is that zoning laws in the US are in most places specifically set up to discourage high density construction and make it unprofitable.

In the early 20th century, zoning laws were first enacted in the US by the so called "Progressive Movement". They observed that the rich enjoyed spacious country estates while the poor lived in crowded, dense slums, so they decided to "help" the poor live in what they deemed better conditions by making it illegal or difficult to build new high density neighborhoods at all.

More on this topic in the book "Living Downtown," by Paul Groth: http://publishing.cdlib.org/ucpressebooks/view?docId=ft6j49p...

Bit of a mischaracterization there comparing turn of the century tenements to high rise apartment buildings.

I wasn't comparing them. I was describing the historical circumstances that led to the zoning laws that still make it difficult to do profitable high density residential development in most of the US, and specifically how the paucity of non-tenement high density apartment buildings is an ongoing side effect of these laws.

> There's gotta be a way to economically make a lack of density untenable.

A revenue-neutral switch to land value taxes?

> Urban sprawl is a threat to the environment, we talk about charging a tax on Carbon, what about on Urban Sprawl?

A carbon tax (as long as cars use energy derived from sources covered by a carbon tax, whether that's fossil fuels directly or electricity produced in some share by burning fossil fuels) is a tax on urban sprawl, since urban sprawl forces longer trips and less-fuel-efficient transportation.

Although it's only a major tax on the commuters, those that live in the area that needs more housing don't have any reason to change their behaviour.