Firstly, it's worth pointing out that, despite the 1960s' hallowed place in rock mythology as the era of all the greats (The Beatles! The Stones! Dylan! The Beach Boys!), as the era when revolutionary new music was released every week...well, 1960s audiences also still listened to whole swathes of music which was trite or commercial or silly or derivative (or all of the above). The version of the 1960s we get as listeners in 2019 is typically a pre-packaged one that tells a story that baby boomers want to portray, for starters. The version of the 1960s we get also typically focuses on the music that sonically represents the time in distinctive ways; if you look at the US single charts, 'All Along The Watchtower' was basically Jimi Hendrix's only biggish hit, and while it (just) cracked the top 20, that week now-much-more forgotten songs like 'Little Green Apples' by OC Smith and 'Girl Watcher' by the O'Kaysions were in the top 5. But something in the sound of 'All Along The Watchtower' says something obvious about its era - ('Vietnam!') - and so it often gets evoked when the era gets evoked in pop culture, whereas OC Smith and the O'Kaysions fall by the wayside.

Secondly, it's interesting that you pick 1967, because it is of course the heyday of one of the great manufactured rock/pop bands: The Monkees. This was a group that was put together for a TV show, and while they played their instruments on TV, it was played by session musicians on the record. And the Monkees didn't write their own songs; 'I'm A Believer' was written by Neil Diamond, 'Pleasant Valley Sunday' was written by Carole King and Gerry Goffin, and many of the big hits were written by the songwriting duo Boyce and Hart (the theme tune, 'Last Train To Clarksville', 'Stepping Stone'). And the Monkees certainly weren't unique in this regard; the Byrds' early backing tracks were largely played by the same broad group of LA-based session musicians as played on the Monkees' music, the 'Wrecking Crew'. The producer (and, now, convicted murderer) Phil Spector, in the earlier 1960s, had Darlene Love sing lead vocals for a few tracks she wasn't credited on (most famously 'Da Doo Ron Ron', ostensibly by the Crystals, who then had to mime something they had nothing to do with on TV).

Where the Monkees were unique was having a popular weekly TV show chronicling their exploits, which was a form of publicity that was basically equivalent to saying "yes, I would like a #1 record, thank you!" (the Monkees released six singles in a row that went into the top 3, from 'Last Train To Clarksville' in 1966 to 'Valleri' in 1968).

The success of the Monkees quickly led to a swathe of essentially anonymous 'bubblegum' bands, mostly notably those produced by the producers Kasenetz and Katz for Buddah Records (the Ohio Express of 'Yummy Yummy' fame, the 1910 Fruitgum Company, The Lemon Pipers), and the music from the TV cartoon The Archies ('Sugar Sugar', which is somewhat different in tone to that more recent incarnation of Riverdale).

As for the promotional activities used to get a song to the top of the charts, one thing that has to be remembered about the 1960s is that - before the days of large multiregional radio conglomerates like Clear Channel - radio airplay was exceedingly regional, and it was common for local acts to have 'regional hits'. For example, the earlier California surf music of acts like Dick Dale and the Del Tones ('Misirlou') often led to large regional successes in California, but didn't translate to the parts of America that weren't surfing crazy.

This ability to have a regional hit meant that it was possible for a small-ish promoter with good relationships with the local pop music industry in an area to identify local talent, and to have a realistic chance of success in a way that's no longer quite as possible. But firstly, the biggest problem for someone promoting a new single is to get a sizeable amount of the public to hear it. People obviously need to know a song exists before they are prepared to think about buying it, and usually they need to hear it a few times. Whether with payola or infectious enthusiasm or the evocation of success (or a combination of all three), record label people would place music by local acts on local radios in the state, some of which would become successful. But ultimately record label people couldn't manufacture hits (in most markets and niches) - radio was still a competitive market, and there wasn't much space for songs that didn't have much instant appeal to listeners. Radio stations of the era didn't have access to information about exactly what songs make people change stations (they do now) but they did have instant listener feedback in terms of people calling into the station, and they did have information about local sales they could use (this was reported in Billboard at the time), and what other stations were playing, and they used this information to guide their programming. Radio DJs - surrounded by pop music all day, getting feedback from callers, knowing about local sales, getting cues from the record label people - often also felt they could pick what songs would be hits in their market, and acted accordingly.

Mark Lewisohn's Tune In portrays the Beatles' record label Parlophone buying promotional time on pirate radio stations that broadcast to the UK (a la The Boat That Rocked), and The Beatles encouraging friends and girlfriends to ring into the radio station to pretend to be excited new fans in order to promote their first single 'Love Me Do', for example, in order to promote Parlophone's new recording act. There's some controversy about this, but the Beatles' manager Brian Epstein is reputed to have bought a large number of copies of 'Love Me Do' in his guise as manager of NEMS, the biggest record store in Liverpool, to try and push the song up the charts and thus get noticed by more people (not that it did the Beatles' chart hopes any good - the way the UK charts were calculated at the time was based on a song's rank at a particular store, rather than overall sales, and 'Love Me Do' would have been the biggest thing at the time at NEMS anyway, given Liverpool's early Beatlemania.) To some extent, the buying of the promo time on the station would have been a signal to the station that the record company intends to invest in this act in a long term way and that it was worth giving the band a shot, even if they thought 'Love Me Do' was a bit unsophisticated, and if the Beatles' Liverpudlian fans were calling in along with their girlfriends (and the Beatles were likely pushing this in their stage banter at the time, of course), the radio station likely gave 'Love Me Do' more of a shot than they would have otherwise.

The Beatles' situation is in the more-homogenous UK rather than the US with its large regional markets, but the same principles largely applied in both markets. In the US, local successes were often then picked up by larger record labels with more of a national reach (whether they were major labels or 'minor labels' - in the 1960s the idea of the Rough Trade-style 'indie label' which deliberately aimed at a niche market which valued a certain sort of artistic integrity had not yet come to fruition - smaller labels were still aiming at the charts, ultimately). To give an example I recently read about, a song by The Falcons called 'I Found A Love' was released in 1962 on the small Lu Pine records in 1962, and the much larger (but still, comparatively, minor) record label Atlantic, with definite national reach and a history of hits, saw promise in 'I Found A Love'. Atlantic made a deal with Lu Pine to distribute the record nationally (if you're a small Detroit-based label, how do you find the capital to print hundreds of thousands of copies necessary to make something a hit, and then how do you distribute those copies to record stores in California and Wyoming and Atlanta? It's way easier to license the distribution to a larger label who takes a cut of the profit - and for the larger label it's not a bad deal either - you don't have to pay for the costs of something with proven hit potential, and maybe the smaller record label will go bankrupt anyway before you have to pay them). And the Atlantic distribution enabled 'I Found A Love' to become a top 10 hit on the R&B charts. Oh, and the reason I was reading about The Falcons was because they were a Detroit-based R&B vocal group whose individual members went on to play a role in hits later also distributed on Atlantic - the group included Mack Rice (who wrote 'Mustang Sally'), Wilson Pickett (whose version of 'Mustang Sally' was the big one), and Eddie Floyd ('Knock On Wood') - and the previous lead singer before Pickett was Joe Stubbs, who was later a member of several Motown groups (and the brother of Four Tops singer Levi) - I found the level of links between Motown and Stax very interesting. But I digress!