 In 1911, Hjort went to Flinn-O'Rourke Construction Company and served as this firm's chief engineer from 1929 until his death in New York during 1944.Under his watch a string of New York City Subway tunnel projects were planned and completed, most notably the Brooklyn–Battery Tunnel between the southern tip of Manhattan and Brooklyn.In 1911, Hjort was among the founders of The American-Scandinavian Foundation in New York City.