Tallgrass prairie is characterized by such grasses as big bluestem and Indian grass. Either of these grasses can easily reach heights of five or six feet, hence the name.
In the United States, when the European settlers arrived, tallgrass prairie was found throughout most of Iowa and Illinois, as well as in parts of North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Missouri, Minnesota, Indiana, Wisconsin, and Michigan. Though both were completely surrounded by forest, sections of tallgrass prairie were also found in Ohio and Kentucky (the later was dubbed the "Big Barrens"), perhaps testifying to an earlier, drier period, when tallgrass prairie had been found much farther east.
Though the settlers originally mistakenly assumed that any soil which could not grow trees was not suitable for farmland, they soon discovered otherwise. Indeed, though it is difficult at first to break the sod, the tallgrass prairie produces some of the most fertile soil available, as the topsoil produced is so full of humus (i.e. decaying organic material, the end result of a compost pile) that it is almost black. The topsoil is also thick, and may be up to eight feet deep in places, owing to the long grass roots which extend deep into the soil.
Today, the tallgrass prairie has been all but destroyed. (In Iowa, for example, more acres of land are used for highway than are dedicated to tallgrass prairie.) What has not been used for farmland has either been overgrazed (a process which encourages the growth of bluegrass and discourages the growth of taller grasses) or has become shrubland or forest, due to poor management. (Prairie needs to be burnt on approximately an annual basis, both to prevent the growth of trees and bushes and to eliminate the dead grass, which may prevent new grass from growing.)
There is a little hope, however, as, in recent years, there has been increasing interest in prairie restoration. Additionally, there is some interest in using prairie grasses alongside roads, both to eliminate mowing expenses and to decrease the risk of roadside flooding, as tallgrass prairie is excellent at retaining water during rainstorms.