This jumped into my hands this last weekend. The maker's mark on the shank was pretty rusty, and I figured it would be some unknown maker; but, to my surprise when I wire-brushed it off, I found "Crescent Tool Co., Jamestown, N.Y." Alloy Artifacts lists this as the K-24 screwdriver, produced from maybe 1914 to the late 1920s. The change of handle from straight to "T" is authoritative: it really snaps into position.
Well worth the dollar I paid for it.