Achondroplasia is one of the most common types of dwarfism. Learn about its causes, diagnosis, and treatment. Achondroplasia is one of the most common types of dwarfism.
Westward Expansion (1807-1912) The Surge West. Summary. The westward movement of the American population occurred in intermittent flurries of settlement. The first began early in the nation's history, resulting in the statehood of Vermont, Kentucky, Tennessee, and Ohio, all of which were admitted to the Union between 1791 and 1803.
Westward Expansion, 1790â1850. In this interactive map produced by WGBH, explore the territorial and population changes in the United States between 1790 and 1850.