Tyler, I stand corrected. However, most of prairie is now farmed or grazed intensively, and even in this article it states only 1% of original grasslands is still real prairie. I think grasslands could only be returned to the long rooted grasses if it is rotationally grazed by hooved animals like the Savory Institute. Agriculture actually destroys the root structure that stabilizes the soil and retains rainfall. Therefore "grasslands" is now in a near monoculture of wheat, corn and soybeans and other crops, and grazed to death by commercial cattle operations.
If everyone could by like Alan Savory or David Bamberger these lands can be restored. It will take a couple of years and some fencing to rotational graze on large enough acreage. I couldn't do it with the 1/3 acre I devote to my horses, that's for sure!
I guess you could call my home former grasslands because I live on the valley floor of the former Valley of the Hearts Delight where stone fruit used to rein before the advent of the computer chip. Elk and deer were the dominant hooved species before the Spaniards built their missions and brought cattle, horses, goats, pigs and sheep with them. The mountains to the west have ecotones with redwood forests and chapparal, the mountains to the east are mostly chapparal, the valley floor used to be meandering streams, grass and oaks.