The 50th anniversary of electroweak unification is coming up in a couple days, since Weinberg’s A Model of Leptons paper was submitted to PRL on October 17, 1967. For many years this was the most heavily cited HEP paper of all time, although once HEP theory entered its “All AdS/CFT, all the time” phase, at some point it was eclipsed by the 1997 Maldacena paper (as of today it’s 13118 Maldacena vs. 10875 Weinberg). Another notable fact about the 1967 paper is that it was completely ignored when published, only cited twice from 1967 to 1971.It is strange to make a big deal out of a 1967 paper, when no one thought it was important at the time.
The latest CERN Courier has (from Frank Close) a detailed history of the paper and how it came about. It also contains a long interview with Weinberg. It’s interesting to compare his comments about the current state of HEP with the ones from 2011 (see here), where he predicted that “If all they discover is the Higgs boson and it has the properties we expect, then No, I would say that the theorists are going to be very glum.”
Usually, if someone solves some big scientific problem, he has evidence in his paper, he writes followup papers, he gives talks on it, others get persuaded, etc. Weinberg's paper was not particularly original, influential, or important. It got cited a lot later, as it because a popular paper to cite when mentioning the Standard Model.
It appears to me that the Higgs mechanism and the renormalizability were much more important, as explained here:
Meanwhile, in 1964, Brout and Englert, Higgs, Kibble, Guralnik and Hagen had demonstrated that the vector bosons of a Yang–Mills theory (one that is like QED but where attributes such as electric charge can be exchanged by the vector bosons themselves) put forward a decade earlier could become massive without spoiling the fundamental gauge symmetry. This “mass-generating mechanism” suggested that a complete Yang–Mills theory of the strong interaction might be possible. ...Weinberg and 2 others got the Nobel Prize in 1979, 't Hooft and Veltman in 1999, and Englert and Higgs in 2013.
Today, Weinberg’s paper has been cited more than 10,000 times. Having been cited but twice in the four years from 1967 to 1971, suddenly it became so important that researchers have cited it three times every week throughout half a century. There is no parallel for this in the history of particle physics. The reason is that in 1971 an event took place that has defined the direction of the field ever since: Gerard ’t Hooft made his debut, and he and Martinus Veltman demonstrated the renormalisability of spontaneously broken Yang–Mills theories.