No city was more of a help to Abraham Lincoln and the Union war effort, or more of a hindrance. No city raised more men, money, and materiel for the war, and no city raised more hell against it. It was a city of patriots, war heroes, and abolitionists, but simultaneously a city of antiwar protest, draft resistance, and sedition.
Without his New York supporters, it's highly unlikely Lincoln would have made it to the White House. Yet, because of the city's vital and intimate business ties to the Cotton South, the majority of New Yorkers never voted for him and were openly hostile to him and his politics. Throughout the war New York City was a nest of antiwar "Copperheads" and a haven for deserters and draft dodgers. New Yorkers would react to Lincoln's wartime policies with the deadliest rioting in American history. The city's political leaders would create a bureaucracy solely devoted to helping New Yorkers evade service in Lincoln's army. Rampant war profiteering would create an entirely new class of New York millionaires, the "shoddy aristocracy." New York newspapers would be among the most vilely racist and vehemently antiwar in the country. Some editors would call on their readers to revolt and commit treason; a few New Yorkers would answer that call. They would assist Confederate terrorists in an attempt to burn their own city down, and collude with Lincoln's assassin.