How far would a 100mw am radio signal go?

The range of a 100 mW AM radio signal can vary significantly based on factors such as frequency, antenna design, terrain, and atmospheric conditions. Typically, AM radio signals can travel farther during nighttime due to lower atmospheric noise and the reflection of signals off the ionosphere. Generally, a low-power AM signal like this might reach anywhere from a few miles to over a hundred miles under optimal conditions. However, in urban areas with interference, the effective range may be considerably shorter.