I took a look at an "old-standby":  "The American Heritage Pictorial Atlas of United States History" [1966].
According to the atlas, these were the points/forts held by the British in violation of the Treaty of Paris - 1783 and not returned to the United States until 1796, after Jay's Treaty went into effect.
 
From east to west ... all of these points except those I was thinking about "to the west" have been mentioned.
 
On/near Lake Champlain:
Pointe-au-Fer in New York, and across the lake, Dutchmans's Point in Vermont.
 
On the St. Lawrence:
Oswegatchie in New York
 
On Lake Ontario:
Fort Oswego and Fort Niagara, both in New York
 
And "points west" what I was thinking about in my original post ....
Fort Detroit and Fort Michilimackinac, both in the North-west Territory in 1796; both now in Michigan.
Fort Detroit is, of course, in the present city of Detroit, Michigan.
Michilimackinac is in present-day northern Michigan, near the present Mackinac Bridge.
 
There might be others, but these were the posts turned over to the U. S. by Britain in 1796 per the American Heritage Atlas.
 
David
 
David Roberts
Hollywood, MD
 
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Subject: Re: [NYHIST-L] Fort Niagara

Point au Fer in northern Lake Champlain was occupied by the British until 1796, within the U.S.