The Mark Twain is Missouri’s only national forest. It includes roughly 1.5 million acres, mostly within the Ozark Highlands. Located across southern Missouri and northern Arkansas, the Ozark Highlands are an ancient landscape. They have large permanent springs. The area has over 5,000 caves. It is made up of old volcanic mountains with many nationally recognized streams. Parts of the Ozarks were never under oceans or glaciers. There are over 750 miles of hiking trails. About 200 miles out of a planned 500 mile Ozark trail have been completed. When finished it will connect St. Louis to the border of Arkansas. There it will connect with the Ozark Highlands Trail in northwest Arkansas. When completed the trail will be over 1,000 miles long. It will run from St. Louis, Missouri to Lake Fort Smith State Park, near Fort Smith, Arkansas.