The distance a scanner is able to receive varies based on the type of scanner, the location of the radio, and many other factors. A portable scanner inside a home may only receive 10 miles or so. A base station scanner with a back-of the-set antenna slightly more. A scanner connected to an outdoor antenna often will receive double or triple these ranges. If you have a portable scanner inside a car, the metal roof of the car will attenuate the signal you're trying to receive. A mobile scanner
antenna mounted outside of the car with a magnetic or other type of mount will significantly increase the distance you can hear and the clarity of most stations.
The distance a scanner will receive depends on many factors including your elevation; the frequency, elevation, transmitter power, and tower height of the transmitting station; the terrain and buildings in your area; whether cellular, paging and other transmitters in your area; whether the system you're monitoring is a wide-area network, and more. Every area and every situation differs. Go to scannermaster.com for antennas, pre-amplifiers and other hardware that will help you increase the
range you are able to receive.
The information for the state and counties listed below is the best information on-hand but cannot be guaranteed to be 100% accurate. Radio frequencies and systems change over time. Some areas have limited reporting on the types of radio systems in use. You may wish to check with local residents and authorities to verify the information below.