
The frontier is the margin of undeveloped territory that would comprise the United States beyond the established frontier line. The U.S. Census Bureau designated frontier territory as generally unoccupied land with a population density of fewer than 2 people per square mile (0.77 people per square kilometer). The frontier line was the outer boundary of European-American …

Uranium mining in Arizona has taken place since 1918. Prior to the uranium boom of the late 1940s, uranium in Arizona was a byproduct of vanadium mining of the mineral carnotite.. California. Uranium was discovered in 1954 in the Sierra Nevada of Kern County, along the Kern River about 30 miles (50 km) northeast of Bakersfield.Two mines, the Kergon mine and the …

Salar de Uyuni (or "Salar de Tunupa") is the world's largest salt flat, or playa, at over 10,000 square kilometres (3,900 sq mi) in area. It is in the Daniel Campos Province in Potosí in southwest Bolivia, near the crest of the Andes at an elevation of 3,656 m (11,995 ft) above sea level.. The Salar was formed as a result of transformations between several prehistoric lakes …

Below are lists of the top 10 contributors to committees that have raised at least $1,000,000 and are primarily formed to support or oppose a state ballot measure or a candidate for state office in the November 2022 general election. The lists do not show all contributions to every state ballot measure, or each independent expenditure committee formed to support or …

The Republic of Colombia is situated largely in the northwest of South America, with some territories falling within the boundaries of Central America.It is bordered to the northwest by Panama; to the east by Venezuela and Brazil; to the south by Ecuador and Peru; and it shares maritime limits with Costa Rica, Nicaragua, Honduras, Jamaica, the Dominican Republic, and …

Uranium mining is the process of extraction of uranium ore from the ground. The worldwide production of uranium in 2019 amounted to 53,656 tonnes. Kazakhstan, Canada, and Australia were the top three uranium producers, respectively, and together account for 68% of world production. Other countries producing more than 1,000 tonnes per year included Namibia, …

Sand mining is the extraction of sand, mainly through an open pit (or sand pit) but sometimes mined from beaches and inland dunes or dredged from ocean and river beds. Sand is often used in manufacturing, for example as an abrasive or in concrete.It is also used on icy and snowy roads usually mixed with salt, to lower the melting point temperature, on the road surface.