I read that the Frontier slot card was the first (I think it was in an article in Tom Pleau's Coast-to-Coast magazine.)

I also heard claim that Harrah's Atlantic City developed the first slot card that tracked players and awarded points.

One other early slot program was at the Golden Nugget-Las Vegas. Insert your card and you get a ticket, redeemable for 50c, for every $75 coin-in on $1 machines. This program did not track players by name in the machine.

In addition there were several pre-slot club era programs with "VIP" identification cards. Usually tracked your play by $ and number of coin-buys from the change persons. (Example, Sahara had a "VIP" card in the Paul Lowden ownership days, prior to Bennett's purchase.)

FYI, I'm about 1/2 way on writing an "introductory" article on slot card collecting for the club magazine. Not to compete with C. Donley's fine book, but just to explain the basics about it.