About 58% of Americans live in urban areas of more than 200,000 people. (Census) However, far fewer than half live in what most folks would consider a "major urban center" or large city. Of those that do, fewer still live in the type of urban environment that you describe, with an efficient transit system that serves the burbs'. I'm guessing based on your location in Northern California that you live near the bay area? If so, that certainly fits (along with places like Boston, DC etc) but even those places are far from bike-friendly in most suburbs.