New England still secedes
I don't understand why everyone seems to be assuming that one small divergence like the date of Jefferson's death is going to change New England seceding from the United States. There were simply to many differences between the regions of the country for them to remain together. It was practically inevitable that they would part ways.
While it is true, as mentioned previously, that England and Scotland have been able to stay together despite their differences, let's not forget that the United Kingdom is a unitary state where secession is illegal. Really, what did the founding fathers expect when they allowed the states to ultimately remain independent entities from the central government.
OOC: Despite what you may think to the contrary, 'coming up with' the real world does not make you witty and imaginative. Why does someone have to do that in absolutely every DBWI. It is always stupid. Seriously, I've been visiting this site for years and years, and in every DBWI I have ever seen someone always thinks, "oh man I will be SO CLEVAR if I act like I just came up with the real world as a time line off the top of my head. It will make fake me in this other world look soooo smart." Well it never does. You always predict World War I for no good reason. Utterly predictable and utterly boring. Sigh.