>So I have to ask, in the 130-or-so year history of electrical circuits, wiring and transmission, has there EVER been a copper shortage so severe that aluminum wiring was actually an economically more viable option?

Yes, see Gorge Andrews's post above. The cost angle drives everyone, hence the current collective barganing issue in Wisconsin. The drawbacks of aluminum wiring weren't really known at the time. Once they became apparent, the rush to aluminum dropped drammatically. Aluminum conductors are much better for high tension transmission lines, except near oceans where salt in the air becomes an issue.

>Is there ANY advantage at all to aluminum wiring no matter how small?

Mostly in cost, although the relative lack of flexiblity is a factor too. I've never heard of finely stranded aluminum cabling like [copper] machine tool wire and [copper] traction motor leads, although this doesn't mean it was never made.

>It is my understanding that aluminum is one of the most common metals in the earth but copper isn't exactly scarce.

The best [room temperature] conductor is silver (Ag), followed by copper (Cu), and then aluminum (Al). Aluminum is /the/ most common metallic element in the earth's continental crusts. It's everywhere, particuarly sand and it's progenitors. Sand is used for making glass, so it's in your windows and computer screens. The problem with aluminum is that it's so active (i.e. large valence number) that it very rarely appears in metallic form in nature, if at all. Until the Alcoa process was perfected, a lump of metallic aluminum was more valuable than a equivalent sized lump of gold or platinum. The alcoa process requires lots of electricity, which is why all the big aluminum plants are in the Pacfic Northwest near the USBR hydro plants (John Day, Grand Coulee, and so forth).

For those of you who collect coins, the silver connection figured into the Manhattan Project. Leslie Groves needed a lot of wires for the electro magnets in the calutrons at Oak Ridge. But the war was on, so copper was difficult to get. So he twisted Treasury's arm to have a lot of uncirculating silver dollars melted down for wires. This is why sivler dollars minted between about 1920 and 1945 are so rare. Last I heard the silver wiring is still in place in Oak Ridge.