This is one of those pieces of tool history that has yet to be researched and documented. The wrench is marked:

RICHARD. MILW. WIS. (Milwaukee Wisconsin)

9/16 CHROMIUM VANADIUM 1/2 

I could find nothing on this maker. Chrome vanadium gained popularity in the 1930s, and I would think this wrench would date to that time. The wrench is made well, and there are no owner markings. 

Wherever possible, I will combine orders into one shipment and charge you the exact shipping cost. This applies to auctions and fixed-price listings.

I bring orders to the Post Office every day: If you receive a shipping notice before 4:00PM Central Standard Time (CST), your package will be at the Post Office that day. If you receive a shipping notice after 4:00PM CST, it will be at the Post Office the next business day (Monday through Saturday).

Please let me know if you have any questions or need additional pictures.