Every shortwave radio I have ever owned has offered four bands: FM, AM (or mediumwave), shortwave, and longwave. The FM, AM, and shortwave bands are always filled with stations (although shortwave less so these days) but the longwave band for me has always been empty. In all my years of attempts at longwave DXing, I have only ever picked up two stations. These same two stations are beacons that endlessly repeat two or three characters in Morse code. I can only occasionally receive their faint signals and they are overpowered by normal electrical interference.
Beacons, specifically non-directional beacons used by pilots and sailors for navigation, are about the only longwave signals I could hope to receive in the United States. Longwave was once widely used for broadcasting in Europe, Asia, and the former Soviet Union. There are still some longwave broadcasters in those regions. For example, the BBC broadcasts BBC Radio 4 on 198 kHz from their transmitter site in Droitwich, England (although the days of that transmission are numbered). But those types of signals are too far away to receive here under normal conditions.
During a six-hour long power outage, I was finally able to make out the Morse code call letters broadcast by those beacons. One of the few good things about a power outage is that it eliminates nearly all of the electrical interference that normally plagues radio reception. By using the call letters and the frequencies, I was able to find both beacons in this list of North American longwave beacons. To my surprise, both beacons are at nearby airports. So it turns out that in all my attempts at longwave DXing, I have never received any station more than ten miles away!