Basically it isn't uncommon to be able to listen to any high powered station from New England to Florida during the day at Cape Hatteras. While on the northern beaches (Nags Head and points north) expect to hear most if not all of NYC's 50kw AM stations. You can hear other lower powered stations up and down the dial from Maryland, Delaware, NJ, Va and Pa. Night-time expect to be able to hear most of the 50kw clear channel (*not the broadcast company, but the FCC channel designations) stations from east of the Mississippi. Night-time reception I found on the Outer Banks to be more prone to reception of spanish formated radio stations.....if I had to guess since I do not understand spanish, most of these stations are probably out of the Caribbean region. So on OBX, what might be clear reception of a 50 kw station say in Elizabeth City NC, might be over run by some spanish formated station from who knows where ...all of this in a span of 20 to 30 miles near/away from the ocean. If I remember correctly, 700 WLW and WCKL 1530 come in at night fairly well. You won't be able to get WCKL 1530 until after sunset as there is a local 1kw daytimer on 1530 licensed to Wanchese (WOBX-AM, broadcast hours are basically from sunrise to around sunset)
I used to work for one of eastern NC's more powerful AM stations from 1994 until 2005, then I moved to NY. I must say, The Outer Banks is the best place for AM radio, daytime long distance reception. Night-time is about as average as any other place in the country.