Dijkstra visited the USA several times before moving to Texas in 1984. In the summer of 1971, he went on a trip to the USA and Canada. It wasn't his first trip to North America, but it was the first time his wife Ria accompanied him. The corresponding trip report was written by Dijkstra on June 23rd, 1971 in EWD312.
Dijkstra went to the Summer Institute on Compilers and Operating Systems, held at the University of Maryland. David Gries lectured about compilers and Dijkstra lectured about operating systems. Afterwards, Dijkstra visited Lehman from IBM in New York, the Niagara Falls, and Toronto.