The westward expansion happened in the 1800`s. It was a period of time when the United States was trying to obtain more states in the Union from throughout North America; it was titled the Manifest Destiny. One of the reasons was because immigrants wanted to come to America to have freedom of religion, uninhabited land, and access to special metals. Martin Van Buren (1837 - 1841), William Henry Harrison (1841, he died of pneumonia in office), John Tyler (1841 - 1845), and James K Polk (1845 - 1849) were all presidents who were supporters of the westward expansion. James K Polk had an especially big influence on the westward expansion, although only half his plans succeeded. Some of his plans also eventually started the Mexican and American War. Meriwether Lewis and William Clark were both soldiers in the US army sent by Thomas Jefferson to sail to the Pacific Ocean and back. Their goals were to find the boundaries of Louisiana, place the sovereignty of the US over tribes by the Missouri River, set up trade, and to declare the Pacific ours before the British could obtain it. The expedition began in 1804 and lasted two years, starting at the mouth of the Dubois River and ending at the Pacific Ocean. They were assisted by George Drouillard who was half Shawnee, half French. The expedition proved helpful to the westward expansion by stating allege over their exact territory.
The next big event contributing to the westward expansion was the Texas Republic. The Texas republic was when Texas wanted to separate from Mexico and become an independent nation. The separate nation existed from 1836 - 1845. Its boundaries were the present day Texas, and parts of New Mexico, Oklahoma, Kansas, Colorado, and Wyoming. Texas and Mexico got into an argument over its boundaries on the southern and western side, with Texas saying it was Rio Grande and Mexico saying the Nueces