Seattle reporting in, downtown is absolutely full of cranes and large-building construction sites.
I think why you don't hear about many cities in America building super-large skyscrapers is threefold: 1) The U.S. is still a very large country with lots of room, especially away from the coasts 2) Construction costs of super-tall buildings scale nonlinearly, so buildings taller than 55 stories tend to not pay off per the square footage value of renting/selling, so mid-scale buildings are generally more profitable 3) Geographic agglomerations mean that creative class folks (like developers) tend to be attracted to existing large cities like SF, Seattle, and NYC