[Cyrien]

First the Lousiana purchase... can't say how that would have gone without a US. Unlikely it would have been sold to England as the French and English were big rivals, which is one reason it went to the US, since at the time relations between England and US were very strained (War of 1812, smuggling, piracy, stopping American commerce vessels etc, colony that just gained independence with French help etc etc etc...)

As for Spain. Very unlikely since large tracks of that land had been Spains just a little while ago which they gave to France due to not being able to afford to garrison it, and of course it came with certain agreements attached, such as we will not under any circumstances sell this land to the United States, blah blah blah. Too bad Spain wasn't a big enough power at the time (a decling power as it where) to enforce the agreement when Napolean sold the land anyway.

It fact it could be argued that without the US purchasing it however that Napolean could not have fully funde his invasions of other countries and might have been forced to stop early... say without Russia in the fold. Which might have allowed for a big change in history with France as a major power.

Alternatly however the USSR almost certainly would still have arisen as a power the British held American colonies probably wouldn't have been as advanced industrialy wise and very doubtfully would have gone any further than the eastern coast of Mississipi all of which would drastically changed the course of WWI and might have superceded WW2 and made it never come to be with a German victory instead of Allied in WWI.

People always seem to forget that though the US didn't enter WWI until very late they profited off of it a great deal as the "Arsenal of Democracy" selling to the British. With British Colonial doctrine being what it was it is unlikely that the USA as colony would have had that kind of production capability, just look at India and Egypt and Australia or other British colonies for what it probably would have been. A source of raw materials for export to the British manufacturing base and a source of young men to be used as cannon fodder, sorry, artillery and heavy machine gun fodder...

In short without a USA the world would either be dominated by Germany, England, France, or the USSR depending on how things went. Despite what many of my fellow US citizens would like to think the US had very little impact on global affairs *read European affairs* until the late 1800's early 1900's. See the Spanish American War and the Chinese open door policy for notes on early US interest in global affairs.

So in conclusion the events of Europe would likely be much the same without a US as they where with a US until WWI or just before it. Then things can get very confusing.

PS: There is no reason Communism and Marx wouldn't have occurred without a US. Marx was based on the European Experience of Industrialization and the Russian Revolution was during the same year that the US entered into WWI. Other than a small expeditionary force that had little affect on the Soviet Revolution the US would not have influenced its outcome or happening in any meaningful way. So there is no reason the USSR wouldn't have formed, just no cold war between it and another Super Power afterwards.