I'm reading a little book I found called "All About Sports Betting", by John Gollehon. It's a super quick read and has some good info, but I came across something that I thought was interesting.

The book was written in 1986, so it's obviously outdated in many ways. One of the points that are clearly out of date, is his section on money-line vs point-spread bets. At one point, the author says, "Why not give baseball a point-spread you ask, as if to suggest that the sports books must all be run by a bunch of morons. Well, it's been tried, but not successfully. And here's why. First, baseball is a relatively low-scoring affair. It's difficult to pick a number that would equally divide the betting public. Secondly, there's more parity in baseball that would make point-spreads unattractive. Thirdly, baseball has been based on odds, not points, since the days of Abner Doubleday. Sports books that have tried a baseball point-spread are plainly going against the grain."

I'm too young to remember betting on baseball without run lines being available, so this made me curious. It must have been after this book was written; but when did run lines become popular in baseball? Was this the result of online operators gaining popularity, or something else?