That's a really easy question to answer: Mexican, until the late 50s when surfers from Cali starting to travel to other places in search of the best surf then there was nothing in the US that wasn't Mexican. Illegal imports to NYC via the port were hash from Turkey and Greece.
The first place the surfers went in the late 50s was Mexico, they packed up the van and drove down the Pacific coast to Sonora, some went further south to Michoacan and Oaxaca. This being the late 50s, Mexico was still absolutely full of weed and there was no enforcement of the laws so the surfers drove into a world of weed.
The surfers weren't able to travel to Hawaii, Asia and other places until the very end of the 50s for the simple reason that jet airline travel didn't develop until then. Remember that the De Havilland Comet was the first commercial jet airliner and it started in 56, the Boeing 707 in 58 so once the jet services started then people could travel to far flung places in search of surf or smokes.
1951 is only 14 years after weed growing was made illegal so if the seed wasn't Mexican then it was domestic US descended from the commercial farming days when they were growing Cannabis Americana for Eli Lilley, Parke Davis and others. I forget where it was exactly now but Eli Lilley had a big research farm in NY state.
So there's your answer, Mexican or a descendant of Cannabis Americana which was mostly Mexican probably too.
There is a long history of Mexican weed in the US and I truly think if you were able to score weed there before the 60s then you were buying Mexican or domestic grown Mexican. The Mormons brought cannabis to Utah in 1917 when they returned there from the Sonora desert to escape the Mexican Revolution, that is why Utah was the first state to enact anti-MJ legislation.
At the same time, many of the early stars of the Hollywood silent screen were down in Mexico fighting for Pancho Villa, Tom Mix the famous cowboy of the silent screen fought for Villa and used to frequently cross the Rio Grande back into the US with his saddlebags full of the finest Sonoran grass to sell it or exchange it for whiskey.
Then there is William Burroughs, he grew Mexican weed in the Texas panhandle in the 40s and wrote about how widespread and common weed growing was in that part of the world, especially among the Mexican Texans.
Mexican however is not Haze, most Mexican varieties will finish at latitudes upto 45N and only take 3-4 months at most to ripen. Remember than the Mormons were able to grow luxuriant crops of Sonoran weed in Utah. Mexico is a big country and covers a lot of climactic zones. Oaxacan Gold is from the south of Mexico and that only takes 14 weeks indoors, Sonora is in the north just below the border so strains from there will be quicker, not grown one myself but I'm told 12 weeks max indoors with some being 10-11.
