California
There are temperate rain forests in the US, for example the Olympic National Forest in Washington State, however the central part of the US is temperate grasslands.
The Midwest?..
Much of the central part of the United States is grassland.
East
There are many grasslands in US : Black Kettle National Grassland Little Missouri National Grassland Crooked River National Grassland Sheyenne National Grassl
mostly in the eastern part
The Southwestern US.
It's very large. Is the US a grassland or bushland country?
The flat of gently rolling land in the central US is called the Great Plains.
The largest National Grassland, the Little Missouri National Grassland in North Dakota, covers 1,033,271 acres (4,181 km2).
Much of the southwestern United States is desert.