It depends on the base. Most Navy bases with military assets have two layers of security. The first gets you into where the housing, medical, exchange, commissary, and Morale, Welfare, and Recreation (MWR) facilities are located (like the movie theater and gym), as well as a credit union branch if there is one. You can pretty much move around this area freely, though someone will likely stop you if you look suspicious.
Then there is an inner base fenced off from the outer base with another layer of security where the military assets are stored (i.e. the piers with ships and submarines as well as maintenance and support facilities for a Navy base). There is a lot more security here.
It was a pretty big deal for my then-girlfriend (who was a Navy Nurse Corps officer at the time), to get into the lower base where my submarine was docked. (This was to visit me in the evening or on a weekend when I had 24-hour duty.)
I assume the other military branches do something similar.
Well, Air Force bases do secure the flight line distinctly from the rest of the base. And mission activities that occur outside the flight line secure access on a building-by-building basis, or (if the facilities are so arranged) by securing a “campus” of related buildings behind a security perimeter in addition to building-by-building.
Some buildings are in the open access area (once you are admitted to the base). “Community Center” facilities like the commissary and the exchange were already mentioned; also in that category is the Military Personnel Flight (MPF, or what used to be called the Consolidated Base Personnel Office or CBPO) because it’s a customer-facing function for all types of military personnel issues regardless of the member’s assigned unit.
And bringing it back around, the base’s Pass and ID office is often in the MPF building.
Interesting. In my time in the USAF (roughly the 1980s) I was always amazed at how much that was not true of stateside bases. The flightline itself, where airplanes sat out in the open was guarded by patrolling armed sentries, but not really physically secured against some kind of crash and smash raid.
And it was not uncommon to have MWR facilities, staff offices, and repair shops full of difficult to replace parts & tools whose loss would quickly affect readiness all jumbled together based on the random walk of history since the base was built.
From what I’ve heard a bunch of progress has been made at at least some bases on the inner/outer base idea as @gnoitall says. More often it seems they’ve built new MWR, commissary, clinic, etc, facilities outside the base proper on new land forming a nearby annex. Moving towards making the entire old base the “inner” secure base that’s all business, no BS.
Before 9/11 every big Army stateside Army base I knew was open. Anyone could drive on. Fort Dix had Route 68 go right through it. Specific areas were behind fences but everything else you could drive around. Navy and Air Force bases were different. Immediately after 9/11 they closed access to Army bases and I haven’t seen a change since. I retired in 2016. My experience is now limited to a few bases around here. I have seen no move away from the base.
I went on a mission to Japan in the early 80s, and our mission was headquartered in Fukuoka. The American mission president would assign missionaries who had military dependent IDs to Sasebo so he could go shopping with them.
How were smaller bases?
My uncle worked at Dugway Proving Grounds as a civilian, and they lived on base. We could visit them but my aunt or uncle needed to give our names and car information to the gate. Was that typical for small bases or was that because of the mission of Dugway?
It would be mission specific. I think Picatinny Arsenal was always a closed base. When I was stationed at Fort Hood anyone could drive on but I worked out of Robert Gray Army Airfield which was gated.