In the Midwest (Kansas, Oklahoma,... etc), the US has seen a massive amount of wind developed in the past few years.

To give you a feel for what I mean, in a few short years, the SPP region went from a small amount of wind to having greater than 60% renewable penetration. This means over 60% of generation serving load came from renewables at one point. ERCOT (grid operator for Texas) has also had really high numbers (upper 50).