Human habitation made have begun in Nevada 20,000 years ago. Explorers in the early 1800s found Mohave, Shoshoni, Washoe, and Paiute Indians living in Nevada. The first European explorer was Francisco Garces, a Spanish missionary, who visited in 1775 or 1776. Fur trappers and traders explored the area around 1825. In 1830, the Old Spanish Trail was established between Santa Fe and Los Angeles, providing access to Nevada for goods from the Southeast. Frémont explored the Great Basin and the Sierra Nevadas between 1843 and 1845. When Mormon settlers under the leadership of Brigham Young settled around Salt Lake City, they created the state of Deseret out of Utah and most of present-day Nevada. They wanted to be admitted as a state in 1849, but instead Congress created the Utah Territory in 1850. Non-Mormons living in Nevada did not want to be placed under Brigham Young's governance and asked for a separate territory. However, the population at the time was only a few hundred. That changed after the discovery of the Comstock Lode in 1859 at Virginia City. By 1860, 6,700 people had crowded into the camps in Carson County. In March, 1861, President Buchanan signed an act that created the Nevada territory. Although lacking the necessary minimum population to become a state, Nevada held a constitutional convention in 1863, but its recommendations were rejected by the voters. Another convention in July 1864 approved statehood, and Nevada became a state in October 1864. The mining industry in Nevada was based on the value of silver. When the federal government limited the use of silver in its monetary system in the 1870s, many Nevada mines were forced to close. The population of Nevada dropped sharply between 1870 and 1880. In the 20th century, Nevada began another boom, based on gambling and entertainment in Las Vegas and Reno.