When did the term "flip flop" displace the term "thong" in North America for a type of sandal?

To Australians like me "thong" means a kind of sandal such as recently repopularized by the Havaianas brand but we know it means a kind of G-string in other English-speaking parts of the world.

To most English-speaking people in the 21st century it seems "flip flop" (or "flip-flop") is the term for the sandal-like footwear.

But several times I've come across suggestions that "thong" used to be used for this kind of sandal in North America.

• I'm pretty sure I came across it in the novel A Confederacy of Dunces, written in 1960s New Orleans. But perhaps it was in another American novel from that era.

• There's this comment on the talk page of the Wiktionary "thong" entry:

  Note: Usage in U.S., particulary Southern California. (Prior to 1980's, perhaps later). Thong is exclusively footware (sandal), not related to undergarments or bathing suits. The usage of thong as G-string (bathing suit or underwear) is post 1980's?

• Etymonline states that flip-flop meant "thong sandal," by 1972; but for thong states:

  As a kind of sandal, first attested 1965; as a kind of bikini briefs, 1990.

As an amateur etymologist and lexicographer I'm very interested to know:

• During which years and which parts of North America were flip flops called thongs?
• Does anybody still call them thongs anywhere in North America?
• Did flip flops only replace thongs due to the latter term picking up the new sense of G string around the 1980s / 1990s?

Or to put it in a single question, What is the history of the term thong as a kind of sandal in North American English?

Solution 1:

I grew up in New York (born in Nov 1968) and when I was a child they were called "thongs". In the very late 70s my family moved to Seattle and there they were also called "Thongs". I only became aware of the term "flip-flops" in the late 80s and found it humorous that a g-string would be called a "thong". (I can still recall my adolescent thoughts regarding the idea of comparing butt-cheeks with toes :)

I now live in Germany, so I may be a bit out of touch with some of the current trends.

I find it interesting that "young people" in America today giggle when we "old people" call them "thongs" and they need to "correct" us.

Solution 2:

I grew up in the Seattle area, 1960s-1970s, and we always called the rubber sandals thongs. I moved to Boston in 1987, and they were called flip-flops, there. When I returned to Seattle in '92, I started hearing flip-flop, and now I never say thong other than around family members who know what I'm talking about.

Solution 3:

In the 1960s and early 1970s in the New York metropolitan area, people did refer to the shoes as thongs. It was from the early to mid-1970s that the transition to the term "flip-flops" started to take hold, with thong becoming the term for a bikini bottom with minimal covering over the derrière area.

Solution 4:

I grew up in Los Angeles in the '80s and we referred to them as thongs. My experience is that flip-flops displaced the word thongs when the underwear became popular in the '90s.