Stations in coastal areas can use higher power at night, as long as they go directional and aim it away from co-channel stations in the rest of the country. (In WWRU's case, that higher power ends up being aimed right over NYC on its way out to sea, coincidentally enough...)
WWRU (and the other stations with higher power at night) puts no more than 1 kW in the direction of any other station on 1660, the nearest of which is in Michigan, if memory serves.