About 1,300 additional Chicago police officers are expected to be spread across the city on New Year's Eve.
Patrol bureau chief Fred Waller said Monday that the majority of the extra officers will be in uniform to increase visibility.
Crowds are expected to gather downtown for festivities which include fireworks displays.
Plainclothes officers also will mingle discreetly with the crowds. Waller says many officers have had off days canceled to work Tuesday night and into early Wednesday morning.
Chicago's downtown Riverwalk will close at 10 p.m. Tuesday. Some streets and bridges near the Chicago River also will be closed.