Atlantic City has a higher crime rate than both New Jersey state and the national average, with violent crime being the highest type. Like most tourist heavy cities, the crime features predominantly outside of the main city in poorer neighbourhoods but you should still be cautious.
It is advised that tourists do not go on to the boardwalk late after dark, especially outside certain casinos. This is as beggars and prostitutes are reported to hang out around these areas. There are separate walkways between some casinos that are safer and should be used when possible.