Early 50s, I believe...there should be a serial number under the bottom bracket that will narrow it down further. If not under the bottom bracket, look on the seat clamp...they put there for a year or two.
The other bikes are CWC, (late 40's) and Columbia, also can be dated by the serial number. The Mr. Columbia site is no more so I don't know where to find their numbers. The CWC numbers are available.