I have some shapefiles which include various points and a corresponding street address, whose lat/lon I've manually found in Google Maps. There is no .prj file.
Google Maps Lat,Lon, unknown coordinate system x, y, city, state
36.7448656,-119.7937943, 6329742.00029, 2155243.06469, Fresno, CA
36.7341137,-119.8126966, 6324144.37016, 2151400.93634, Fresno, CA