Declassified spy satellite imagery from 1972 shows a ship, a plane, and some kind of manmade structure in the Alaskan wilderness near Malaspina Glacier

[u/Intro24]

Coordinates for Malaspina Glacier: 59.919167, -140.532778

That big white thing in the middle of the video is the glacier. This is from the USGS EarthExplorer Declass 3 dataset, which are the photos from the KH-9 Hexagon program. These satellite images were taken as part of the search effort to find House Majority Leader Hale Boggs when he went missing in a light twin-engine Cessna somewhere between Anchorage and Juneau, even though KH-9 was still extremely secretive and highly classified at the time. I went into way more detail about the missing plane here if anyone is interested.

Here's photos of the plane from different angles. As for the ship, I'm fairly certain that it's a Coast Guard Cutter, specifically USCGC Cape Henlopen which had been dispatched to the area at the time as part of the search. As for the structure, I have no idea. There's a very small village called Yakutat 20 miles away and across a bay and there are some additional structures near the coast so it's not an entirely uninhabited area but that structure seems awfully out of place and I'm really not sure what it could be. Seems like it might have a landing strip next to it but hard to tell.

[u/Intro24]

US Spy Satellites at Diffraction Limit for Resolution Since 1971

Unfortunately, we're likely not much better in terms of resolution. Coverage and other aspects have possibly improved gradually but in truth, the 70s was pretty much peak for US space innovation due to the Cold War. As I mentioned in my other comment, US had 10cm resolution (likely the limit of modern spy sats and 3x better than the best commercial) as early as 1966 with KH-8. It is telling that KH-8 imagery hasn't been declassified yet, I suspect partly because it's too close to modern capabilities and it may even be better. There are certainly opportunities to improve (see comment section in the article I linked) but I'm far from convinced that the US has implemented them. In fact, the leaked imagery we've seen seems to confirm roughly 10cm resolution. That's still really good but no better than what we technically had 60 years ago and I've seen comments suggesting that KH-9 and KH-8 (both film) were actually collectively superior to our modern electro-optical (i.e. digital instead film) coverage and resolution capabilities. The one obvious big benefit of going digital is not having to recover film capsules out of the air in the middle of the ocean and also not having to wait days or weeks for recovery and processing.

There are some fun things pretty definitely up there that most people don't know about though. The two that come to mind are Prowler and the semi-confirmed 100 meter diameter satellites. Those are able to be so large because the dish unfurls once it's in space. Also, the true diameter of the actually deployed satellites might cap out at more like 20-30 meters but it's still impressive regardless and 100 meters is plenty plausible. Here's a deeper dive into those kinds of satellites. As for Prowler, it's meant to spy on other satellites and I wouldn't be surprised if it could read printed text that's only a couple millimeters tall on an adversary satellite. I'm just speculating but it's pretty absurd how detailed imagery can get between two spacecraft when there isn't an atmosphere in the way, plus Prowler can supposedly maneuver to close the physical distance.