www.google.com type in "Past US Open Cup Winners" hit the I'm Feeling LUcky button answer in less than 2 seconds
NASL did not participate in the USOC. The Open Cup was an amateur-only tournament until MLS came along.
The NASL might not have competed but I don't think it was because of their being pros. In the early years a bunch of professional teams won it like Bethlehem Steel.
As far as i know NASL teams could have entered but choose not to. They had nothing to gain and everything to lose if they lost. They could have lost because their were a lot of very good club teams operating at the time. NASL teams played friendlies and lost to these teams from time to time. The good clubs did pay their players per game basis. I don't think any team has won the open that did not pay it's players. The team that won the most opens in a row was Greek America. First cup was won by a team from Brooklyn. NYC teams won many and finished 2nd many times as well.
1914 Brooklyn Field Club 1915 Bethlehem Steel 1916 Bethlehem Steel 1917 Fall River Rovers 1918 Bethlehem Steel 1919 Bethlehem Steel 1920 Benn Miller FC (St. Louis) 1921 Robins Dry Dock (Brooklyn) 1922 Scullins Steel (St. Louis) 1923 Patterson (NJ) 1924 Fall River SC 1925 Shawsheen SC 1926 Bethlehem Steel 1927 Fall River SC 1928 New York Nationals 1929 Hakoah All-Stars NY 1930 Fall River SC 1931 Fall River SC 1932 New Bedford 1933 Stix, Baer & Fuller (St. Louis) 1934 Stix Baer & Fuller (St. Louis) 1935 Central Breweries 1936 1st German-Americans (Philly) 1937 N.Y Americans 1938 Sparta ABA (Chicago) 1939 St Mary's Celtic Brooklyn 1940 Sparta ABA 1941 Pawtucket FC 1942 Gallatin Pittsburgh 1943 Brooklyn Hispano 1944 Brooklyn Hispano 1945 Brookhattan N.Y. 1946 Vikings (Chicago) 1947 Ponta Delgada (Fall River) 1948 Joe Simpkins (St. Louis) 1949 Morgan-Strasser (Penn) 1950 Joe Simpkins 1951 German-Hungarians (Brooklyn) 1952 Harmarville (Penn) 1953 Chicago Falcons 1954 New York Americans 1955 Eintract Astoria 1956 Harmarville 1957 Kutis (St. Louis) 1958 Los Angeles 1959 San Pedro Canvasbacks 1960 Ukranian Nationals (Philly) 1961 Ukranian Nationals 1962 New York Hungarains 1963 Philadelphia Ukrainians 1964 Los Angeles Kickers 1965 New York Ukrainians 1966 Philadelphia Ukrainains 1967 Greek-Americans NY 1968 Greek-Americans NY 1969 Greek-Americans NY 1970 Elizabeth SC 1971 New York Hota 1972 Elizabeth SC 1973 Maccabee LA 1974 Greek-Americans NY 1975 Maccabee LA 1976 San Francisco AC 1977 Maccabee LA 1978 Maccabee LA 1979 Brooklyn Dodgers 1980 New York Freedoms 1981 Maccabee LA 1982 New York Freedoms 1983 New York Freedoms (2 CONCACAF semi-final places) 1984 AO Krete NY 1985 Greek-Americans SF 1986 Kurtis SL 1987 Espana (Washington D.C.) 1988 Busch SL 1989 Kickers St Petersburgh 1990 Chicago Eagles 1991 Brooklyn Italians 1992 San Jose Oaks 1993 CD Mexico 1994 Greek-Americans SF 1995 Richmond Kickers (PDL) 1996 DC United (MLS) 1997 Dallas Burn (MLS) 1998 Chicago Fire (MLS) 1999 Rochester Raging Rhinos (A-League) 2000 Chicago Fire (MLS) 2001 Los Angeles Galaxy (MLS) 2002 Columbus Crew (MLS) Source: http://www.nhsoccer.com/Open Cup.htm
Gallatin Pittsburgh For any history buffs / Pittsburgh locals: Does anyone have any information on the Gallatin Pittsburgh team that won the Cup in 1942? My in-laws are from southwestern PA and know nothing about soccer. The one time they raised an eyebrow is when I mentioned Buff Donelli, a U.S. player in the 1930s who also coached the Pittsburgh Steelers. There is an Albert Gallatin School District where they live and I was curious if there was some connection. Thanks.
Re: Gallatin Pittsburgh I'm willing to bet that when that information becomes available, you'll find it here: http://www.sover.net/~spectrum/
If I'm not mistaken, my grandfather played on several winning sides in the mid30's. He was with Fall River. How's that for a legacy???