The Empire of New Jersey timeline is one in which New Jersey seceded from the Union during the First World War, although the POD dates to the American Civil War and various sour grapes. The Empire was originally the Free and Independent State of New Jersey, or alternately the Garden Empire.
New Jersey's contempt for Abraham Lincoln is greater than in OTL, and people not only reject Lincoln twice in elections, they take to the streets about it. The Independence Movement is born and simmers over the next few decades. Woodrow Wilson took over the movement in 1905, and he uses discontent over the tensions surrounding WWI to secede from the Union, along with other states, during the Great Secession.