Colt, Remington Rand and Ithaca manufactured 1911A1s during WWII. There was a test contract for Singer: they are very rare and command thousands. Union Switch and Signal manufactured a few thousand: I forget the number. I believe Remington Rand made the most 1911A1s and Colt was the second leading producers.
High Standard may have subcontracted some parts like barrels but never built complete pistols.
Prior to World War I, Springfield Armory built some 1911s. Colt built most. Remington-UMC built a few 1911s perhaps and a Canadian outfit (North American Arms?: I forget: I think they were working in the old Ross Rifle Factory). Most of the Colt substitute WWI contracts were cancelled prior to any meaningful production.
AutoOrdnance was purely commercial, and the modern commercial Springfield Armory variations I believe are built on Brazilian forgings from an old government plant I believe, and assembled in the US. (I'd guess it's privatized in Brazil but am not 100% sure about that.) It's possible now that the parts are US built: I am no expert on that company's history.
After World War II, other subcontractors provided some replacement slides, typically for National Match guns but I don't believe there were any new frames built between 1946 and the adoption of the Beretta 92 25 years ago.
I must say I am confused about the current 1911 situation in the US military: some new ones from different manufacturers may be being procured in relatively small lots for specialist units. Would LOVE to see an article in the gun rags today that accurately clarified who (if anybody) is using M1911/1911A1s today and all the current manufacturers and/or refurbishers.
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