I'm kinda fascinated by the history of the M1 carbine, how all these companies that didn't normally make guns ended up manufacturing them. And I know pretty much everyone was involved in the war effort during WWII. Are there any good comprehensive resources about what companies made what war materials? Everything from guns to vehicles to uniforms and field gear. Books/websites/etc.

Freedoms' Forge
Hyde, Charles K. Arsenal of Democracy: The American Automobile Industry in World War II.

From wiki for Arsenal of Democracy:

United States armament manufacturers

The spending on military production was distributed 32% for aircraft, 14.8% for ships, 25.6% for ordnance (guns, ammunition and military vehicles), 4.9% for electronics, and the remaining 22.7% for fuels, clothing, construction materials, and food. Note that production costs fell steadily—the same item cost much less to produce in 1945 than in 1942. The largest United States military prime contractors are listed below in order of the total value of munitions produced from June 1940 through September 1944. These large firms produced many different items; the aircraft companies assembled parts made by thousands of firms.

General Motors, trucks, tanks, aircraft parts
Curtiss-Wright, aircraft engines
Ford Motor Company, trucks, aircraft
Convair, aircraft
Douglas Aircraft Company, aircraft
United Aircraft, aircraft parts
Bethlehem Steel, ships
Chrysler, tanks, electronics, trucks
General Electric, electrical parts, engines
Lockheed Corporation, aircraft
North American Aviation, aircraft
Boeing, aircraft
AT&T Corporation, telephones
Glenn L. Martin Company, aircraft
DuPont, chemicals, ammunition, atomic bomb parts
U.S. Steel, steel
Bendix Aviation, aircraft parts
Packard, aircraft engines
Sperry Corporation, electronics
Kaiser Shipyards, ships
Westinghouse Electric Company, parts
Grumman, aircraft
Newport News Shipbuilding, ships
Republic Aviation, aircraft
Bell Aircraft, aircraft
Vigor Shipyards, ships
Nash-Kelvinator, parts
Studebaker, trucks
Consolidated Steel Corporation, steel
Goodyear Tire and Rubber Company, tires
Esso, gasoline & oil
Avco, aircraft parts
International Harvester, trucks
American Locomotive Company, tanks
Western Cartridge Company, ammunition
American Car and Foundry Company, tanks
United States Rubber Company, rubber parts
Continental Motors, Inc., aircraft parts
Sunoco, gasoline & oil
Baldwin Locomotive Works, tanks
Pressed Steel Car Company, tanks
Permanente Metals, incendiary bombs
RCA, radios
Caterpillar Inc., tanks
Allis-Chalmers, parts

Union Switch and Signal makers of switches and signals for railroads, made 1911s.  I'd love to have one as a railroader, but they're somewhat rare.

And of course Singer the sewing machine company, made M1 Carbines (and maybe 1911s?)

Sinister, thanks! Great info. I came across Freedom's Forge in a quick search, I will have to look into both of those books.

Singer didn't make any complete M1 Carbines. They made receivers as a subcontractor for Underwood - these are marked Underwood but have a "B" stamped on the rear of the receiver.
http://m1family.com/underwood-carbine-registry-t83.html

They made 500 M1911A1 pistols as an 'educational order" but never entered full production.
https://www.thetruthaboutguns.com/holy-grail-1911s-singer-1911a1/

Rockola made M1 carbines. The juke box company

I don’t know of a comprehensive publication.  

Fact is EVERY company switched to wartime production.   Certainly in USA, Germany, and Japan.

The M1C was made by Rochester Postal Meter.  Stocks by Trimble.  Larry Ruth’s book on the Carbine lists suppliers for each final assembly plant, and if you dig into the history of each you’ll see most were only remotely involved in the type of manufacturing they did during the war.  

One of my buddies, a researcher on the Browning MGs, showed up at the building that made the M2 tripods for the Buffalo Arms 1919s.  He asked to get in the basement; the president said they don’t have a basement, and my buddy informed him yes, you do.   Most people now have no idea that every building was wartime production.

M-1C was made jointly by Griffin & Howe and Springfield.  Unhardened receivers were sent to G&H which then drilled and tapped the receivers for their scope mount.  The units were sent back to Springfield for hardening (which caused some mounts to warp).  The metallurgy of the mounts were changed by G&H to fix it (as well as making the mounts sturdier).

Was anything interesting found in the basement?

For weapons, I'd have to say the M1 Carbine had the most eclectic mix of oddball ''who'da thunk it'' manufacturers.

Considering it was supposed to have the firepower of a pistol, it was quite a novel concept.  Not as novel as the intermediate cartridge (like the Jap. 6.5 mm or the 7.92 kurz) and the Stgw, but uniquely American.

In my small town, the cigar factory supposedly switched to making parachutes.
My mother worked there briefly before getting married to her 1st husband and having kids.

After Ford turned down the Brits to make the Merlin Engine, it was produced by Packard. The reliance on Detroit to enable the Allies eventual victory has been overlooked by many. Notwithstanding the ability of applying mass production to military production. This is what Saginaw Steering Gear did to the Browning 1919A4:


Take a look at Willow Run, a plant that mass produced B-24's. Even more, parts went from hand fit to interchangeable.

It's a rabbit hole, but a very interesting one I fell into a couple of years ago. Still working on it.

Freedoms Forge - Arthur Herman
The Arsenal of Democracy - A.J. Baime
Arsenal of Democracy - Charles Hyde

International Harvester made more than just trucks during the war. They made M1 Garand rifles too. I have a lot of family that lived in the Quad Cities area -Rock Island, Moline, etc. They all either worked at International Harvester or worked at the Rock Island Arsenal during the war.

IHC didn't make M1's during WWII.  They made them in the mid 1950's.  The only M1 manufacturer's during WWII were Springfield Armory and Winchester.  International Harvester and H&R produced theirs after the Korean War.

The mosquito bomber was designed so funiture manufacturers could make many if it's parts. The amazing part is how creative manufacturing had to get. Machine tool production lagged production increases by a good deal. Plus there was the mandate at the time to send machine tools over to the USSR to upgrade their manufacturing. Americans and British became real good making custom gadgets and jigs that made it possible to get a lot done with little.

One has to acknowledge a tremendous debt of gratitude to Edsel Ford who was the mastermind behind the conversion and coordination of our industrial base to a wartime footing.  And he did it all for free.   Sadly his accomplishments are little known and having a failed car model named after him added to the obscurity.  

Eastman Kodak:
- Complex prism system used in the Norden bomb sight.
- Various optical products including binoculars and a really neat, for it's time, 1x rifle scope that allowed to soldier to shoot with two eyes open while projecting crosshairs showing where the rifle was pointed.  
- The proximity fuse used in AA shells.
- Various films and cameras, but that was their bailiwick anyway.  
- They also made a hand grenade that was supposed to explode on contact, but it had less than stellar reliability and never made it into mass production.  It was round instead of the pineapple shape used at the time.  The purpose was to prevent the grenade from being thrown back by the enemy.
- They also did various neat thing for the Manhattan Project.

Louden Manufacturing, Fairfield, Iowa

from Wiki
During World War II, the company reached record production levels, fueled by demand for the company's overhead handling equipment, including the improved Louden "Super Track" monorail systems. Military applications of Louden Monorail included its application for material handling devices used in the manufacture of the first atomic bomb at Oak Ridge, Tennessee, and for material handling in a B-29 bomber plant in Marietta, Georgia.[1][4][7]

We lived on a farm south of Fairfield. Dad got a 352 draft number and as he was already farming 110 acres he was able to work a night shift at Louden's during the war. He mostly welded PSP runway steel panels for the Pacific airfields.

My Grandfather farmed east of Fairfield and he had a classic Louden designed barn with a lot of Louden equipment for hay handling, milking parlor and milk storage equipment. Also had 4 stalls for his Percheron(?) horses he farmed with.