WHO broadcasts with 50,000 watts, the maximum power permitted for commercial AM stations, around the clock. It uses a non-directional antenna. WHO dates back to the early days of broadcasting and is a Class A clear-channel station. During daytime hours, its transmitter power and Iowa's flat land (with near-perfect soil conductivity) gives it at least secondary coverage of most of Iowa, as well as parts of Illinois, Missouri, Nebraska, Kansas, Wisconsin, Minnesota and South Dakota. At night, the station adjusts its coverage to protect fellow clear-channel station WBZ in Boston at nearby 1030 AM. Even with this restriction, it can be heard across much of North America at night with a good radio, but is strongest in the Central United States. It is Iowa's primary entry point station in the Emergency Alert System.