What is the time span between the opening of the west by means of the Louisiana purchase and the end of the western frontier?

The Louisiana Purchase occurred in 1803, significantly expanding U.S. territory westward. The western frontier is generally considered to have ended around 1890 when the U.S. Census Bureau declared that the frontier line no longer existed. Therefore, the time span between the opening of the West through the Louisiana Purchase and the end of the western frontier is approximately 87 years.