I remember gels in the late 70s. I remember that they had sample size cans that were cheap, probably 10 cents, so I bought one. Not sure what I thought I was going to do with it as a 9 or 10 year old. If I remember correctly, the brand was Edge.Turns out Trac II came out in 1971. There is an on-line reference to gels first coming out in the 70s, which is not very precise.