New cities in the mid west are spread out over wide distances assuming automobile transportation.
Denver and the surrounding suburbs come to mind and Calgary in Canada as well.
More than 90% of the city was built in the post-car era, and the main city planning stage (in the 50s and 60s during the population explosion) was of course, heavily car-centric. That's the legacy we're still living out, with similar stories in cities across North America.
I live in a developing "15 minute city" that encompasses a border with Denver and one of its neighboring cities. Development has been... okay I guess. We have a light rail stop that goes downtown to Union Station and to all the main stadiums, and bike trail that runs alongside it.
That's pretty much it. The area has been zoned for everything a 15 minute city might need, but developers have been reluctant to build anything beyond 5+1 apartment buildings and small townhome developments. It's hardly a 15 minute city and both municipalities (Denver and the other) that have a stake in the development don't seem to care much about the area.
We are still fully car dependent for basic errands, and now that they are enforcing parking laws for blocking hydrants, alleys, etc, people are up in arms.