to the OP: which historic events do you want to change? We could speculate a vastly different world based on one or a handful of seemingly small changes.
WWI was easy ish because the US joined due to there trade being attacked. So it doesn't matter if it's the US or Mexico. Due to Perl harbor not happening I don't think they will be joining at all, or at least not till a much later date.
On that note, someone said that Germany had a relative peace with Russia. All I can find is that Hitler had been promising to invade Russia on his campaign trail, is there a reference for this tentative Aly/peace with Germany and Russia before Germany tried to invade?