The ideal dam site is Hoover Dam. One dam at a narrow point created a large lake with a high drop for power generation. No population to displace; the surrounding land is desert. Few other sites in the world are that good.

There's nothing anywhere near that good left in the US. China has some good hydro sites in the west, and they're building hydroelectric dams there. Million-volt DC lines going thousands of kilometers are being used to move the power to the loads in eastern China.