Almost as many people commute by bicycle in greater Copenhagen as do those who cycle to work in the entire United States.
Do you cycle in space? That sounds awesome.
That said, you are right. E.g. I live in Finland, and biking is more popular in Oulu (which is way up north, but on former seabed and completely flat) than in Helsinki (which has a more temperate climate, but is on exposed bedrock and has small-scale hills up and down all the time).
Not to mention, of course, that many cities in the USA are also high-density. In fact, a large percentage of people living in NYC and the like don't even own a car. They are endangered and have to endure pollution and the extra charge on their rent for all the free parking and road space taken up primarily by people that descend onto the city from outside of some suburban American hell. They clearly don't want to live in that kind of place, yet they think nothing of forcing their four ton suburban onto others.
What you are seeing is people in cities realizing they don't want to continue subsidizing some suburban middle class dream and be killed and endangered in their own city in the process.
It's also not feasible for everyone to afford to be able to live downtown in a walkable city with the way cost of living is increasing, and gasp some people may even prefer to trade a commute in a car for not having to live in a box, or have a little space/land to raise a family, grow a garden, etc (the solution there being better rail networks).
And you know what? The cities that started doing that years ago (like Portland) are now blanketed in bike lanes, bike thoroughfares, and bike-friendly infrastructure that makes the city thick with non-car commuters.
On some streets (North Williams and Vancouver, for you Portlanders), the bike lanes are always full. You can sit there and watch hundreds of bikes roll by in an hour. That's a lot of traffic that, 10 years ago, would've been cars.
So, yeah, it does take time.
Start lobbying your city to start it today. 10 years from now, it's a whole new world.
I've noticed this because I ride bike to work regardless of weather, and in January in Finland, that means I'm almost alone on those nice bike paths (which are fairly well cleared of snow).
Portland etc may be slightly more convenient in terms of climate, but still I imagine winter will cut down the number of cyclists.
I live in Arlington, VA, directly across the river from D.C. Now that it's getting to be spring again, I've been noticing far more people walking and biking places. When it rains or snows, I've also noticed the foot and bike traffic are drastically reduced.
We definitely need the capacity to handle inclement weather in our transportation network.