After seeing the last map, this one won't be surprising. Most of the geothermal potential in the U.S. is concentrated in the Western half of the country, and it's where most existing and future projects can be found.
The states in red all either have existing geothermal plants, or planned ones. The numbers in white represent the number of megawatts of capacity for the existing plants, and the yellow numbers are a range of megawatts for planned capacity. California is by far the current leader (with 2.7 gigawatts), but Nevada also has huge planned capacity. You can see a bigger version of this map here.
Total installed capacity is 3,386 MW, and total planned capacity is 2,511 to 2,606 MW.