Tuberculosis (TB) Tuberculosis (TB) Active tuberculosis (TB) is very contagious. The World Health Organization (WHO) estimates that one-third of the world's population is infected with the bacteria that cause TB.
With an average elevation of 6,800 feet, Colorado is the highest state in the United States. A mountain lake outside of the skiers dreamland of Aspen, Colorado. The US is bordered to the north by Canada and Mexico to the South. With 50 states of varied sizes, US is considered the largest nation in America.
Although a few higher unincorporated settlements exist, Leadville is the highest incorporated city in the United States. At an elevation of 10,152 ft (3,094 m), it lies right at the edge of timberline, which in Colorado is from 11,000 to 12,000 feet.