So in 1803, Napoleon gets a little testy or something and doesn't sell Louisiana to the USA. It gives it back to spain; Haiti shows that the New World isn't anything but trouble.
A lot of conflict in the US was over the expansion of slavery - Missouri Compromise, Kansas-Nebraska, etc. - if the US is limited to its original Revolutionary War boundaries, what is the conflict over slavery? Is there none at all (well, is it nothing compared to OTL) ?