Rush is the king of talk radio. Back in the seventies I was listening to Neal Boortz in Atlanta on am 640. He was real good, a libertarian.
He was not syndicated and I don't think there were any syndicated talk shows at that time.

Talk radio was going nowhere, slowly.
Limbaugh hit Atlanta in 1989, he was also on am 640. And he was syndicated when he made it in Atlanta he was then on in about 200 cities. Limbaugh revitalized talk radio.
Boortz got the idea, and when he got syndicated and was on about 340 stations.

Today Limbaugh is on about 640 stations, Hannity on about 600 and Dave Ramsey is third, on about 580 stations. Without resorting to google that is a pretty good look at the lineup.

Boortz never failed to praise Limbaugh and called him "The Godfather."