How Were the Western States' Borders Created?

Land Purchases

• The U.S. government acquired large swaths of land via direct acquisition The Louisiana Purchase from the French -- in 1803 -- was the first and largest acquisition. Land was also acquired in the 1840s through the Texas Annexation, Mexican Cession and the purchase of the Oregon Territory.
  
  

Petitioning for Statehood

• Lands acquired in the 19th century did not automatically turn into states. Most states formed when their citizens petitioned for statehood, and borders were determined through acts of Congress. Legislation sometimes specified that the new state's borders follow latitudinal and longitudinal lines.
  
  

Clarifying the Boundaries

• Surveying errors and inexact legal descriptions led to many boundary disputes. Border agreements determined via topographical features often superseded previously written legislation.