For those you use Alternate History in your games (for example GURPS Infinite Worlds) or just simply fans of the genre like I am. The Alternate History forum is one of premiere location on the internet to find great stories and discussions on alternate timelines.
Even in this excellent forum there are a few timelines that stand out. One of them is Decades of Darkness by Jared. You can view the full thread here or look at the website here
It start with the unexpected the death of Thomas Jefferson in January of 1809. Because of the political confusion the Embargo Act is prolonged longer than in our time line. This cause the New England states to become more embittered at the federal government than the case in our history.
In the aftermath of the War of 1811 (this is not a mistyping) the Five New England States (Maine was part of Massachusetts) plus New York and New Jersey seceded from the United States to form the Republic of New England under the protection of the British Empire.
The loss of many of our history's free states skews the balance of power in the United States toward the slaves resulting in a much darker history for this country. Ironically the histories of two nations; Germany and Russia turn for the better in this time-line.
700,000 words words later the timeline has reached the ending point in 1933. with a situation very different than what we saw with the inauguration of our 44th president.
Timelines like this are great because their authors approach them rigorously and solicit commentary on the plausibility of events. If you read the later posts you will be scratching your head as how this could possibility be. Start from the beginning you will see how the future of the Decades of Darkness was built brick by brick.
I contributed a series of posts that was accepted and edited by Jared detailing the early history of rocketry in the Decades of Darkness (better metallurgy lead to faster development)
I even started my own time-line and continued it for a few post until my writing time was chewed by the various Judges Guild and Points of Light projects I took on. You can read what I did here. Basically the challenge is to create a maximum United States encompassing nearly all of North Amercia without the brutality of the Decades of Darkness time-line.
Although frankly with the loss of South Carolina and Georgia in my alt-Revoluntary War I am not sure how things are going to play out if I pick up again. The general idea is that a solid American VICTORY at Guilford Court House keeps Cornwallis in South Carolina with his army. His grand plan to move into Virigina is scuttled as he recupurates.
The ending battle of the war is nstead in New York City where Geogre Washington force Henry Clinton to surrended with the help of Admiral DeGrasse Fleet. The resulting peace leave 11 colonies independent and South Carolina and Georgia in the hands of the British.
The great Loyalist migration after the peace does not go into Canada. Most head to Carolina and Georgia and smaller number lands in Nova Scotia. Resulting in a nearly empty Upper Canada and simmering resentment in Nova Scotia.
The problems that erupted under the Articles of Confederation in our time-line are magnified in this time-line. This results a new western state, a civil war in North Carolina, a genocide in Pennsylvania, and the shooting of Benjamin Franklin. Then to top it all off the United States has to fight the 2nd War of Independence.