Conversation so far:
What did Vladimir do in the United States?
The Nabokovs settled in Manhattan and Vladimir began volunteer work as an entomologist at the American Museum of Natural History.
Did he do other work after that?
Nabokov joined the staff of Wellesley College in 1941 as resident lecturer in comparative literature.
Did he like this job?
The position, created specifically for him, provided an income and free time to write creatively and pursue his lepidoptery.
Did he stay at Wellesley?
The Nabokovs resided in Wellesley, Massachusetts, during the 1941-42 academic year.
In September 1942 they moved to Cambridge where they lived until June 1948.

Question: What happened after 1948?
Self-contained rewrite: What happened to Nabokov after 1948?