Big, WILD brook trout are often just measured in pounds and not inches and there's still a place or two in Northeastern areas of the US where an angler can actually have a decent chance at catching some. I can think of one Maine river in particular.
Salter or sea run brook trout are indeed rare in the US anymore. Interestingly, Cape Cod also still has a couple of sea-run brookie streams left, and there's been some active TU restoration projects on them. There's also "Coaster" brook trout which are Great Lakes brook trout that live in some of the Great Lakes and move in and out of the tribs for spawning. There's also ongoing efforts to restore these brook trout strains as well.
The Hungry Trout in Wilmington, NY has access to an area within the Adirondacks called the Twin Ponds Preserve. It's actually 3 ponds that is said to hold wild brook trout still measured in pounds. You have to book a trip through them though to gain access but it seems like an affordable and wonderful experience fishing with a guide in a classic Adirondack guide boat on a classic Adirondack trout pond, like the days of old.
Oh and speaking of God's River and more particularly God's Lake. Growing up I knew a kid whose grandfather made an annual trek to God's Lake for giant Northern Pike and Lakers. The photos were amazing.
Any of you guys ever see some of the footage of legendary PA flyfisher Joe Humphries fishing some extremely remote and brawling brook trout rivers in Northern Canada? I think it was in parts of Labrador. Great footage and the rivers were not for the faint of heart.