Hemingway described it quite well in a short story titled The Gambler, the Nun, and the Radio. It was first published in 1932. Probably one of the finest writers of that century describes it here.
"In that hospital a radio did not work very well until it was dusk. They said it was because there was so much ore in the ground or something about the mountains, but anyway it did not work well at all until it began to get dark outside; but all night it worked beautifully and when one station stopped you could go further west and get another. The last one that you could get was Seattle, Washington, and due to the difference in time, when they signed off a four o'clock in the morning it was five o' clock in the morning at the hospital; and at six o'clock you could get the morning revelers in Minneapolis. "