The Black Hills cover an area 125 miles long and 69 wide in western South Dakota and eastern Wyoming.  They include rugged rock formations, canyons and gulches, open grassland parks, tumbling streams, deep lakes, and caves.  Mountain bikers will find many hundreds of miles of old mining and logging roads crisscrossing the region, and nearly 200 miles of single track coursing through some of the most rugged and scenic areas.  Trails range in difficulty from very easy to quite technical.  The mountain biking season in the Black Hills extends from April well into November.