The document lists important dates and events related to westward expansion in the United States from the 1600s to early 1900s, including the establishment of the original 13 colonies, key land purchases and acquisitions like the Louisiana Purchase and Gadsden Purchase that expanded U.S. territory westward, and events that encouraged migration like the Oregon Trail, Mexican War, and Gold Rush, culminating with the annexation of Alaska and completion of the Panama Canal in the early 20th century.