Nope- not stamped with USA or brand name, just the size.
Early sockets had a trapezoid shape on each side of the size stamping.
Other early sockets have a 5-pointed star on each side of the size stamping.
They didn't mark any of those hex drive sockets with "U.S.A" that I know of - that's pretty much exclusive to Dunlap, Walden and G.M. Mfg. Co. on those hex drives, if my memory is serving me correctly.
Don?
an oldie with stars below: