It's not just rumored, but entirely true. The company THA, which was founded by F.P. Journe and Denis Flageollet in 1989 (Vianney Halter would join later) developed the cal. UN 38. The movement was a special request by Ulysse Nardin and Franck Muller and then finished by Jaquet SA. After the Jaquet affair, the company become La Joux Perret. F.P. Journe sold the rights to produce the movement to LJP. Journe is mostly likely the man who designed it.

If I'm not mistaken, the symbol on the dial under the Elgin logo meant the 7 ball bearings that were used in the "Micromatic" movement, which was probably just a marketing gimmick. I'm not really sure if 7 vs. 5 ball bearings made an appreciable difference in the winding capabilities/efficiency of the rotor 😂

Thank you! Most likely Illinois since the movement went out of production about ca. 1963.

This watch has a VERY special Elgin movement, at least for me 😎. Elgin is one of only 2 companies to ever produce an automatic winding movement in the USA (the other being Bulova). They are probably the only company to produce an automatic movement with only American-made parts, hence the "American Made" designation at the bottom of the dial.

The movement in the watch is most likely the Elgin cal. 760; a chronometer grade movement adjusted to 6 positions with a free sprung balance and a very high jewel count (30 functional jewels, not just there for show): http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&a&2uswk&Elgin_760

These movements were some of the last movements made by Elgin before they closed up shop in 1968, and they were reserved for Elgin's highest end line; the Lord Elgin.

Hello! Sorry for the very late reply, I haven't been on in a while lol. I'm still very thrilled with the watch! It keeps pretty dead on accurate time (1-2 seconds fast per day). It does run that accurately over the full duration of the power reserve (5 days). Did you end up buying it?

The watch probably dates prior to 1958 when Elgin introduced their "Durabalance" balance wheel assembly, but after 1947 when they introduced their "Durapower" mainspring.

The logo on the OP's watch stands for Elgin's "Durapower," which was the name for their mainspring with a stronger proprietary alloy that was supposed to be more efficient at winding the watch.