Have you seen other american cities outside of NYC and Chicago? LA is walkable in a lot of places,plenty of side walks. Southern cities are particularly atrocious because even if they were walkable, the heat makes walking impractical in the summer (which can be > half of the year).
Live in Houston, and no we're not. The only break we get from punishing heat is hurricanes and floods, but that often comes with significant power loss throughout the area, making the heat even worse.
Also live in Houston; the heat is uncomfortable but is nothing that some Gatorade Zero can't fix. It's a walkable enough city if you live in the loop. Not NYC walkable but not nothing. Outside of the loop; forget about it! A small price to pay for being able to wear shorts and sandals all winter!
No, we're not. been wanting to take a walk for ~2 months now and couldn't because of the heat. Maybe in more inland cities it is nicer, but within ~200 miles from the ocean it is unbearable.