The 192 million acres administered by the Forest Service for multiple use; comprised of 155 national forests (in 117 units) with 187 million acres, 20 national grasslands with 4 million acres, and 112 other units (e.g., purchase units, land utilization projects, research and experimental areas) with about 500,000 acres. While the NFS lands are concentrated in the West, the 25 million acres east of the 100th Meridian (the Great Plains) make the Forest Service the largest land manager in the East.