The 1916 presidential election in the U.S. was actually pretty close - as in, a few thousand votes in a key state, say, California, could have swung the election to Charles Evans Hughes, the Republican. It just so happens that the margin of victory for Wilson in California was about 3,000 votes. It also happens that Hiram Johnson, then governor of California, did not endorse Hughes for President.
It turns out that Johnson's snub of Hughes was based on a perceived snub - Hughes and Johnson stayed at the same hotel shortly before the the election, and Hughes never said hello to Johnson, a slight that Johnson took personally. As a result, Johnson never gave Hughes his endorsement, and Wilson won California narrowly, by a margin that suggests - wait a minute, would Johnson's endorsement have won the election for Hughes? And if it did, how would life have changed for Americans?
For one thing, kiss the eight-hour work day goodbye, or at least an attempt to eliminate it would be made - I know Henry Ford was a proponent of the eight-hour work day, and he supported it for business reasons (decreased absenteeism, increased productivity, etc.) Also, Hughes was more pro-military than Wilson, even thinking that Wilson was letting the Germans push the U.S. around - so I guess we can forget about staying out of WWI in this case. However...
...the Treaty of Versailles was partially Wilson's baby, so I don't see as much support for it, as the U.S. takes its marbles adn goes home after the war, leaving Europe to sort out its own situation.