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The IBM 2250 Display Unit was originally shipped with the IBM 1130 computer, introduced in 1965. The 2250 could also be attached to IBM 360-series mainframes, as ours was to the 360/91. Like most IBM terminals, attachment was via control unit (or in this case, direct channel) rather than communication port.
The 2250 was the "first commercially available graphics terminal" if you don't count the DEC PDP-1 display (1961). As late as 1971 there were only about 1000 interactive CRT graphic terminals installed in the USA, compared with 100,000 line printers, 50-100,000 Teletypes, and 70,000 "alphanumeric terminals" (such as the 2260) (CACM Vol.14 No.1, January 1971, p.60).