My hometown's near a Nike missile site that was manned during the Cold War. The reason for this positioning is that we were near both a major urban center and a government research facility which had been high-profile for decades. Both of these needed protection in the event of an attack by Soviet bombers.
Now, from what I've read (in our case), it appears that the missiles were to be used only against bombers attacking either the research facility or the urban area. The local towns were less important; there was no sense in wasting missiles on bombers hitting them if it would leave the prime targets undefended or without sufficient weapons. To justify sending equipment and funds to create a Nike base, there must be some location that would be targeted by the Soviet Union.
Check out a map of the Minnesota Nike launch sites:
Image courtesy of Wikipedia user Bwmoll3 under the Creative Commons Attribution-Share Alike 3.0 Unported license.
The sites are clustered around Minneapolis/St. Paul, to protect the Twin Cities population center and general industrial area. According to Wikipedia, the Nike missiles (in the Zeus B (XLIM-49A) form) had a range of 250 miles. By some rough eyeballing, the Canadian/American border is, at its closest, a bit over 250 miles away from Minneapolis/St. Paul, making it impossible for this missile site to effectively protect the cities - unless a Soviet bomber made an approach from the north, which would be the likely attack route. However, the site would still be redundant, given the four sites around the Twin Cities.
Are there any other potential targets in Minnesota? Here's a present day population distribution (I'm assuming that during the Cold War, the population, though less, had roughly the same distribution):
Image courtesy of Wikipedia user Ravedave, under the Creative Commons Attribution-Share Alike 3.0 Unported license.
I can't find any other major population center I would deem important enough to be protected by Nike missiles.
What about other targets? Well, out of the military facilities in Minnesota, only one, Baudette Air Force Station (closed in 1979) is close to the United States-Canada border. It was a radar station - so certainly important for detecting attacking aircraft - and part of the SAGE radar network, sending data for the Duluth Sector. But after looking over a bunch of maps, it seems that there's nothing else in northern Minnesota: No nuclear reactors, key military bases (besides Baudette), industrial centers, etc. I can't find a complete list of ICBM launch sites without ending up on a government watchlist, so I can only speculate that there aren't a lot.
In fact, this site (I'm not sure of its reputability) show virtually no potential possible targets in northern Minnesota, though some in the central and southern part which could be defended by the Twin Cities launch sites.
In short, I can't find any reason to justify building a secret launch site by the Canadian border in northern Minnesota. I apologize to the Minnesotans out there, but it's just not worth the extra funds. I could have missed something, but I doubt the US government would ever build a site in this area.
Now, could there still be secret Nike missile sites elsewhere in the country? Perhaps. In some places, it could be helpful to have a couple more. But that's just for really important targets. You deploy weapons where they're needed most.
Additionally, as DJClayworth pointed out, it's fiction. You get to make things up. If I were you, I'd be tempted to create a fictitious military or research installation of moderate importance - something which the Soviet Union would maybe like to destroy but which wouldn't be so important that soldiers refusing to launch the weapons would have a drastic impact.
Some things you could have this facility do:
- Manufacture special parts for important aircraft or equipment
- Have something to do with the ICBM network in this part of the nation
- Develop new technologies for the military
- be a nuclear reactor
Those are just some starters.