After the birth of their three children, Barker took a more financially stable position developing a First National Bank of Boston branch in Buenos Aires, Argentina.
In order to return to the United States, he then took a position at Sears & Roebuck Co., in which he developed the concept of “time-payment” financing, which became popular in other banks and companies.
Barker made a significant impact on the business world, but his endeavors in international affairs are lesser-known.
In 1948, he travelled to the Middle East to help reseafinancial viability of Iran's "Seven-Year Plan"rch and write the final report for Overseas Consultants pertaining to the to reconstruct the economy.
Alfred A. Knopf Sr. wrote the Chicago Tribune after his death, recalling Barker as a "remarkable" man and close friend, and sharing his achievements outside of business: "He had a great interest in linguistics, speaking Spanish as well as he did English, and being at home in French and German and able in Italian and Portuguese.