ppi
Valley, its dominant economic interest, the merchants and sailors of the
northeastern States and the staple producers of the southern sea-board
were a commercial appanage of Europe. The significance of the
Mississippi Valley was clearly seen by Jefferson. Writing to Livingston
in 1802 he declared:

There is on the globe one single spot, the possessor of which
is our natural and habitual enemy. It is New Orleans, through
which the produce of three-eights of our territory must pass
to market, and from its fertility it will ere long yield more
than half of our whole produce and contain more than half of
our inhabitants. . . . The day that France takes possession of
New Orleans fixes the sentence which is to restrain her within
her low-water mark. It seals the union of two nations who in
conjunction can maintain exclusive possession of the ocean.
From that moment we must marry ourselves to the British fleet
and nation . . . holding the two continents of America in
sequestration for the common purposes of the united British
and American nations.[188:1]

The acquisition of Louisiana was a recognition of the essential unity of
the Mississippi Valley. The French engineer Collot reported to his
government after an investigation in 1796:

All the positions on the left [east] bank of the Mississippi
. . . without the alliance of the Western states are far from
covering Louisiana. . . . When two nations possess, one the
coasts and the other the plains, the former must inevitably
embark or submit. From thence I conclude that the Western
States of the North American republic must unite themselves
with Louisiana and form in the future one single compact
nation; or else that colony to whatever power it shall belong
will be conquered or devoured.

The effect of bringing political unity to the Mississippi Valley by the
Louisiana Purchase was profound. It was the decisive step of the United
States on an independent career as a world power, free from entangling
foreign alliances. The victories of Harrison in the Northwest, in the
War of 1812 that followed, ensured our expansion in the northern half of
the Valley. Jackson's triumphal march to the Gulf and his defense of New
Orleans in the same war won the basis for that Cotton Kingdom, so
important in the economic life of the nation and so pregnant with the
issue of slaver