The purchase of Louisiana a great area west of the Mississippi river from the French in 1803 has sometimes been said to be the cause of the westward expansion of the United States, but the Louisiana purchase has been better interpreted as the occasion for the expansion rather than its cause; for, as Lewis Evans of Philadelphia long ago recognized (1749), whoever gained possession of the Ohio Valleythe chiet eastern part of the central plainswould inevitably become the masters of the continent.
That part which lies east of the mountains was included in the Louisiana Purchase of 1803 and became successively a part of Missouri Territory in 1812, of Nebraska Territory in 1854, of Dakota Territory in 1861 and of Idaho Territory in 1863; that which lies west of the mountains became successively a part of Oregon Territory in 1848, of Washington Territory in 1853 and of Idaho Territory in 1863.
The westward expansion of the United States made necessary American ports on the Gulf of Mexico; consequently the acquisition of West Florida as well as of New Orleans was one of the aims of the negotiations which resulted in the Louisiana Purchase of 1803.
In Louisiana alone (as the state is known to-day), out of all the territory acquired from France as the Louisiana Purchase in 1803, was the civil law so established under French and Spanish rule that it persisted under American dominion.
But this movement of hunters, trappers, traders, Mormons, miners and homeseekers left nothing to show of settlement in Kansas, for which, therefore, the succession of Territorial governments organized for the northern portion of the Louisiana Purchase had no real significance.
From the surplus of the Louisiana Purchase Exposition was constructed in 1914 the Jefferson Memorial costing 8485,000 and devoted to the collections of the Missouri Historical Society.
Bowman, The Administration of Iowa, a Study in Centralization (New York, 1903), an able presentation of the present administrative system in the light of its historical development; William Salter, Iowa, the first Free State in the Louisiana Purchase (Chicago, 1905); B.