[2] Dengis worked as a seaman until his emigration to the United States in 1926; he settled in Baltimore, Maryland, where he became a steel mill worker.
[3][4] Later, he worked as a toolmaker and airplane mechanic for the Glenn L. Martin Company, a job he held until his death.
[4][5]: 257–258 Dengis took up running in Baltimore; he placed fifth at the Port Chester Marathon in 1932 and fourth in 1933 before scoring his first victory in 1934.
[6] After gaining US citizenship in October 1935, Dengis entered 1936 as one of the leading candidates to qualify for the American Olympic team, but in both of the Olympic tryout races (the 1936 Boston Marathon and the 1936 AAU championship marathon) he suffered from medical problems; he failed to finish in Boston, and dropped from the lead to eighth place in the AAU race.
[2][12][13] He repeated as national champion in 1939, breaking the Yonkers Marathon course record with his time of 2:33:45.2; the race also served as a tryout for the ultimately cancelled 1940 Summer Olympics in Helsinki.