Interweaving threads... I'm on board
The "Strung-Out Camelot" suggestion upthread is not far off one possible explanation and if you got
really tight you could bracket it between "McRepublican" getting elected into an atmosphere of inflation and white backlash in '73 ousting the now-damaged Bobby and then pick up with some different elements: either Iran or Saudi implodes faster by '78 or so introducing fundamentalist strains in to replace the earlier vulgar-Marxist Arab nationalism in the Middle East (plus an oil shock and possible US entanglement which would define the start of an "Eighties" different from ours but a different era, just a "Long Weekend" from getting out of Southeast Asia to getting ensnared in the Persian Gulf), quicker metastatization of Silicon Valley around the Homebrew Club and slightly faster work at Intel (up the road from me these days...) that gets them working chips by '78, plus the potential deaths or irrevocable ill health of both Brezhnev and Hua leading to usurpation of power much faster by reformers in both Moscow and Beijing ready not just to introduce Chinese sweatshop power to the global economy but perhaps
muzhiks with MBAs as well, and only a short window of "classical" détente as we're familiar with it between solid Cold War under the Kennedys (if Jack lives for two terms there's probably more of Ruthless Robert left and he's more suspicious of Kosygin's overtures in the late Sixties) and a different kind of "Cold Peace" where the US and Soviets deemphasize confrontation in Central Europe and on the nuclear front as each opens up northern and southern fronts respectively fighting Islamic extremists (Afghanistan, the southern SSRs, and possibly Iranian-held parts of Azerbaijan for Moscow, Saudi and Bahrain and southern Iran -- and God forbid, Pakistan -- for the US) where the new calculus is how to do that without panicking the other side into thinking you're turning on
them next rather than the troublesome Islamic radicals. All of that latter part would lead to a long-term regime of higher oil prices distinct from the shorter-term price shock we know from '73 and possibly more Club of Rome-style economic regimes in both West and East turning towards alternate (nuclear and natural gas?) power resources and much more public awareness of political contests between monetarists and full-employment types in shaping political coalitions. That whole deal could give you a
really short "Seventies" of about six years or so, just a weird little interval between more clearly defined eras.
Or you could have a "long Seventies" instead that was defined around a "mini-party system" defined either by a strong hand of Nixonian Republicanism, or by the steady rise of the New Right facilitated by but ultimately overwhelming the more purely Nixonian "carrier" of the phenomenon. In version one of that, you're basically in a "no Watergate" scenario (except it's not that simple; as the great Jimmy Breslin pointed out in
How the Good Guys Won: Notes from an Impeachment Summer there were
so many things Nixon did that were shady in '71-'72 that Tip O'Neill warned his then-boss Carl Albert in early '73 that impeachment was coming, he just didn't know which set of charges would be the cause.) Nixon does his eight years, maintains his control and for that time at least corrals the New Right into being a substantial faction of the party but essentially short-circuits the powerful and defining connection between the Sun Belt New Right and the Southern New Right by pursuit of the Southern Strategy. Then Nixon's VP post-Agnew, whoever it is, beats Reagan in '76 and you have continued Nixonian policy on through the decade, probably with more and more of its downside leaking out as you get into the successor's administration, and then a collapse at the end where the pendulum swings towards the Dems and the New Right manage to get "their man" nominated in 1980, just in time to be another Goldwater swamped by an antithetical consensus. Or, you could have the New Right rising the whole time as Nixon does his thing like OTL and falls to Watergate/the Chennault Affair/the planned Brookings break-in/whatevs like IOTL, followed by the Nixon-lite of Ford but with the New Right pressing ever more in constituency candidacies, displacing liberal-to-moderate Rs in Congress, winning platform fights at the national convention, and maybe Ford
does ask Reagan to run with him and pulls it out in '76, then deals with the troubles of the rest of the decade as his administration leans further and further to the right (ex. tries to appoint Bork to replace Potter Stewart, uses force to prop up
Somocismo without Somoza in Nicaragua, leans away from détente after getting SALT II sorted out, etc.) Then 1980 brings in party fatigue, economic and foreign policy woes, and Reagan can't quite get over the finish line
but the GOP has been in large part transformed at the institutional level into a party of the Right, run by New Rightists and Dixiecrats with a rump of pragmatic Bob Dole-style conservatives and the Chaffees and Weickers and Hatfields forced into a kind of John Andersonesque Progressive third way or simply out of office. That would be a "Long Seventies" of, like 1969-80/81. And with assorted related cultural movements, more sense of national decay even than in OTL's Seventies, more active protest and identity-justice movements against a persistent Republican government, and a steadier drift to right-wing economic policies that make unemployment and deindustrialization larger and broader fixtures of the decade on beyond the coal and steel industries.
Then there's my own interpretation of OTL's historical periodicity. In terms of American history I believe in a "short Fifties" that starts around late 1951 or 1952 once it's clear there will be no unconditional victory in Korea, as Truman's approval rating tanks and as Eisenhower gains steam against the last sally of the Old Right under Bob Taft, as the Russians work on the H-Bomb and coherent all-day scheduling of TV begins to take shape, and some of the first key civil-rights cases begin to work their way up the appeals process. I would put the end of that "short Fifties" by late 1958: the troops have been in Little Rock making it clear that the federal government and massive-resistance states are going to square off; Sputnik has been launched and the Space Race is on; Castro is taking over Cuba and changing the calculus of the Cold War while also driving the domino-theorists; styles are changing too especially with Modernist furniture and the narrow-lined men's ties and suits of the Sixties already "in"; black-and-white psychological dramas like
Anatomy of a Murder and
Tea and Sympathy are challenging the Hays Code and opening up the possibilities of the Sixties along with anti-hero Westerns like
The Searchers; proper rock and roll is here to stay as Chuck Berry and Buddy Holly and such dominate the kids' charts and start even with the twentysomethings to displace the brief golden age of Nelson Riddle-backed Sinatra, Ella Fitzgerald, and Nat King Cole; Jack Kennedy begins looking seriously at a 1960 presidential run and so does Hubert Humphrey; and so on. Actually the Sixties are so "long" I would say that like the movie adaptation of
Harry Potter and the Deathly Hallows "the Sixties" comes in two parts. One runs from 1958 to 1965 and is concentrated on the sleek, go-go, jet set fashions and celebrity of over-30 icons from the Kennedys to James Bond to Richard Burton and Liz Taylor and so on, on the hottest parts of the Cold War, on the most dramatic and consequential period of change in the Civil Rights movement, and the definitive period of decision on a massive American commitment to Vietnam. Then 1966 through 1972 is
both the era of the Counterculture and of its victorious opponent white backlash, of "Nixonland" and national breakdown, of the cancer of Vietnam, of the disjointed combination of "Volume 1 Sixties" events like the moon landing happening within months of "Volume 2 Sixties" events like Kent State. The whole 1971-72 period is the rotting fruit of "Volume 2 Sixties" at its 'finest.'
Then "the Seventies" really honestly arrive in January 1973. Nixon's inaugurated for his second term seemingly at the height of his powers but really about to collapse. The New York and London stock markets start a two year collapse that costs forty-some percent of NYSE's real value and
73 goddamn percent of FTSE's in London. The overheated easy money of Arthur Burns' "let's reelect Nixon" policies at the Fed, plus some disruptions on the commodities markets, doubles inflation in the first three quarters of '73
before the OPEC embargo and middle-class families can't find enough steak on the shelves for Sunday dinner. Watergate, which had been there for six months of '72 buried under pundits' encomiums about how wise and bipartisan Nixon was plus whispering campaigns about McGovern (and McG's own incompetence re Eagleton) now goes off like an atom bomb. The OPEC sheiks pull off the largest transfer of wealth from a single economic cause up to that point in history. A series of other corruption scandals from Serpico's testimony in NYC to the Sharpstown banking scandal in Texas and many points inbetween rocks state and local politics. The "steel crisis" caused by cheap and better-made Japanese and Korean steel on global markets starts. People start buying Toyotas. Fashion, already into garish colors thanks to mainstreaming hippie chic, now goes to absolute hell in a handbasket. The Seventies are on.
And they carry on in two phases too, I think. The first is the "Sixties Hangover" phases, which is basically Watergate a nd the Ford Administration. The bleakest, most dystopian pop culture and the worst fashions of the decade come from that period, when it all seemed to be coming unglued -- and at the same time there was an undercurrent of "revenge movies" like
Dirty Harry and
Death Wish and a profusion of hard-line cop shows, thankfully forgotten behind more thoughtful and enduring fare like
Columbo and
the Rockford Files, but there were plenty of incipient Reagan voters watching
Police Story and the like. Then comes the "Making of the Contemporary World" Seventies as certain key trends loosed in the first period 1973-76 really take shape and come together. These are diverse. They include the emergence both of politicized Islam and its shockingly sudden relevance as an alternate worldview alien to Cold War calculus, both Sunni (Grand Mosque takeover, the near-massacre of the US embassy in Islamabad,
mujahedin v the Red Army, the impetus towards Sadat's assassination) and Shia (Iran, Iran, Iran, but also flickerings of
Hezbollah in Lebanon.) There's the coming together of the brain trusts of the microcomputing industry and Intel's "microchip." There are significant refinements in packet switching and architecture in both ARPANET and the British equivalent that laid the foundations from which Berners-Lee and company "built the Internet" at the end of the Eighties and brought it public in the Nineties. There's the birth of the modern blockbuster and its transformation of Hollywood corporate culture, presaged by
Jaws but
really a child of the later Seventies. There's the first renaissance of geek culture from Trekkies to
Star Wars to sci-fi on tv to the epic-fantasy explosion to the popularization of Tolkien to D&D to the first proper video games. There are the first stirrings of what will later be the "New Democrats" movement in the candidacy of a nuclear engineer turned peanut farmer with a preternaturally big smile. And in his political destruction there's the first coherence of modern multimedia right-wing propaganda, designed to destroy the legitimacy of any Democrat in the White House and drown them in negative coverage. There's the emergence of the Religious Right, who along with the Birchers are the first "ultra" movement on the American right, dedicated to either owning the system or burning it down and birthing many ideological children and stepchildren down to the Tea Party, the Freedom Caucus, and the alt-right. There's the definitive victory of the New Right in gaining control over the GOP in the '78 and '80 election cycles. There's the flourishing of both hard-core monetarism and "neoliberalism" (which is simply Liberalism, in its 19th century guise, under a clunky name and with all the same flaws and appeal to the meritocratic classes.) There's the creation of the end-of-decade economic conditions that will break the union movements in just about every Western nation that's not West Germany or Australia (well, Japan had their own deal going.) There's the Pacific Rim emerging as an economic force. So much of our world is birthed in that 1977-early 1981 period.
That gets at my end for "the Seventies." So it goes from January 1973 to January 1977 for the first, half then January '77 to March of 1981 with the second. Why then? A number of defining transitions for the creation of "the Eighties" happened in mid to late 1980, though not quite all yet. (You could also do a "long Eighties" from the anti-Carter midterms, the beginnings of revolution in Iran, and the birth of hip-hop after the looting during the '78 New York blackout, but I just roll a different way

). But what cements "the Eighties" as underway is March 1981. The codas of many late-Seventies elements from Apple getting done with the essential work for the Apple II to the cancellation of
Battlestar '80 to the end of the PIttsburgh Steelers' dynasty to the Tehran hostages coming home, had already happened. But the Age of Reagan, so crucial to "the Eighties" was cemented in March when he survived Hinckley's assassination attempt and in a fit of fellow-feeling Congress passed his disastrous FY 81-82 budget. At that point "the Seventies" are truly dead (and disco too

). Some of their influences linger like the first wave of Atari games and
Raiders of the Lost Ark and such, but it's the Eighties for sure by spring of '81.