Junction Interstate #20. - Photo highway signs North to cities of Pecos, Texas, Odessa, Texas. North to Monahans Sandhills State Park. Monahans Sandhills State Park consists of 3840 acres of sand dunes, some up to 70 feet high. Activities include camping; hiking; picnicking; equestrian; bird and wildlife. Texas Camel Treks are held at the park. Texas / New Mexico State Line to Junction Highway # 17 at Balmorhea