Check out this thread which has lots of history on the platypi in the US and Europe:http://www.zoochat.com/2/why-no-platypus-zoos-outside-australia-214993/ The last platypus in the US was at the Bronx Zoo in the 1950s. Tim May posted this info on the earlier thread: On 28th April 1947, one male (“Cecil”) and two female (“Betty” & “Penelope”) platypuses went on exhibit in Bronx Zoo. “Betty” died of pneumonia on 6th September 1948. The other two both lived much longer, the female "went missing" on 1st August 1957; the male died on 18th September 1957. Three more platypuses, a male and two females, arrived on 7th June 1958; these did not do well, the longest living of these died on 25th March 1959.
According to Lee S. Crandall’s classic book The Management of Wild Mammals in Captivity (1964) the last platypus in Bronx Zoo died on 25th March 1959. See this thread for further information about the New York specimens:- http://www.zoochat.com/2/why-no-platypus-zoos-outside-australia-214993/