[2] At the conclusion of his course, he visited Italy, leaving Trieste aboard the SS Saturnia on September 20, arriving in the Port of New York on October 4.

[4] Having graduated from Princeton and unable to travel to Rome on account of the war in Europe,[5] Cain moved to New York to join the firm of McKim, Mead & White.

In June 1941, Walker Cain married Abby Jane Huston (the marriage was dissolved by divorce).

A reporter for the Times noted that the 1974 edition of the Social Register "contains few surprises," while observing that, As usual, some names have been dropped and others added, as a rule through marriage to people already listed...Arthur A. Houghton Jr., board chairman of Steuben Glass, and his former wife, Mrs. Elizabeth McCall Houghton, both remarried in 1973 and their new spouses, the former Mrs. Nina Rodale Horstmann, and Walker O. Cain, a New York architect, were welcomed to the fold.

In his entry in Who's Who in America, 1972-1973, Cain listed among his built works projects completed before McKim, Mead & White’s dissolution in 1961.

Among the many examples are drawings he made of the collegiate chapter houses of St. Anthony Hall (aka Delta Psi fraternity) for their 1947 membership directory.