There are 16 Lockheed 12A aircraft on the U.S. registry that TailWiki has a page for. Every one is built from the public FAA record — year, serial, engine, home base, and registration history — and owners and pilots add photos, trips, and stories on top. The ones listed here were built between 1936 and 1941.
N33650
1941 Lockheed 12A
Wilmington, DE
N25628
1940 Lockheed 12A
Carson City, NV
N2633
1940 Lockheed 12A
Morrisville, VT
N17399
1939 Lockheed 12A
Anaheim, CA
N93R
1939 Lockheed 12A
Baldwin Park, CA
N14999
1938 Lockheed 12A
Leesburg, VA
N18097
1938 Lockheed 12A
Jacksonville, FL
N16085
1937 Lockheed 12A
Punta Gorda, FL
N18125
1937 Lockheed 12A
North Salt Lake, UT
N18130
1937 Lockheed 12A
Neustadt
N18137
1937 Lockheed 12A
Kansas City, MO
N33RA
1937 Lockheed 12A
Canby, OR
N2072
1936 Lockheed 12A
Jackson, GA
N100JT
Lockheed 12A
Flagstaff, AZ
N18906
Lockheed 12A
Dana Point, CA
N4001
Lockheed 12A
Boyce, VA