John Martin Reservoir lies within Dakota sandstone formations stretching from Denver, Colorado, to Tucumcari, New Mexico. During the Cretaceous period, this region bordered lakes, swamps, and inland seas, and the shores of that ancient seaway served as a route for migrating herds of duck-billed dinosaur whose tracks were left behind 100 million years ago and were revealed during a drought year when the lake was low. Today ducks and other migratory birds still follow this route. The region’s first people, the Paleo-Indians, traveled on foot, hunted small and big game, and coexisted with many now extinct animals. In the 1540s, Spanish explorers brought horses to the plains, and during the next century horses radically changed the life and travel of Plains Indians by moving faster and pulling heavy loads. The earliest documented Spanish-Colonial expedition through this area was that of Lt. Zebulon Pike in 1806, and Pike first reported seeing the Rocky Mountains in this immediate vicinity. Early Santa Fe Trail travelers wrote of buffalo herds 50 miles long and 20 miles wide. After Mexico won independence from Spain in 1821, trade between Mexico and the United States began on the Santa Fe Trail, and in 1821 William Becknell, called the father of the Santa Fe Trail, became the first trader to travel from Missouri to Santa Fe on Colorado’s Mountain Branch of the trail. On February 14, 1880, as the railroad arrived, a Santa Fe newspaper declared, “The Old Santa Fe Trail Passes Into Oblivion.”