The first is that slavery would have been abolished sooner. And this is not a debatable point. England had abolished slavery before the American Revolution and abolished it in all of its colonies except India in 1834, with India following along in 1843. The Emancipation Proclamation didn't formally abolish slavery in the United States until 1865. I'm sure Alex would probably say that who cares about an extra 22 years of non-slavery, but I think that's a pretty dumb argument. So Dylan's first point is absolutely correct. If we were still in the British Empire, slavery would have been outlawed sooner, and possibly even without a civil war being needed to do it.