Tesla cars aren't union made, but they are the most American made

• Every year, Cars.com assembles a list of the most American-made vehicles.
• Last year, Tesla only claimed the two top spots. Now it has the entire top four.

Tesla may not have ads featuring American icons like the Wild West, bald eagle, or stars-and-stripes galore, but it's still the most American car brand, at least based on its manufacturing.

For the third year running, Elon Musk's electric automaker took the top prize in cars.com's "American-made index," sweeping the top four spots with its entire lineup. Last year, Tesla only had the top two spots.

Ford, GM, and Chevrolet didn't even crack the top 10.

The survey takes five primary factors into account: final assembly location, origin of parts, origin of engines, origin of transmissions, and manufacturing workforce.

When it comes to electric vehicles, things are starting to change. To qualify for a $7,500 tax credit, new EVs and their batteries must be mostly assembled in the US — something that's benefitting Tesla greatly so far. Tesla is set to receive billions in other credits, too, thanks to its early investment in manufacturing stateside as other automakers race to catch up.

Supply chains are an interesting quirk in the EV transition, and are made even more complicated by the union-made versus non-union-made tensions, especially as politicians like Rep. Alexandria Ocasio-Cortez enter the fray. In September, she said she was looking to trade in her Tesla for a union-made vehicle to support striking auto workers as they work towards a new contract with Ford, GM, and Jeep-maker Stellantis.

As work remains stopped at plants where workers are represented by the United Auto Workers, Tesla's non-unionized workforce remains in production, giving Elon Musk yet another edge over domestic competitors.

These are the top 10 cars on the American-made index and where they are manufactured:

1. Tesla Model Y: Austin, Texas and Fremont, California
2. Tesla Model 3: Fremont, California
3. Tesla Model X: Fremont, California
4. Tesla Model S: Fremont, California
5. Honda Passport: Lincoln, Alabama
6. Volkswagen ID.4: Chattanooga, Tennessee
7. Honda Odyssey: Lincoln, Alabama
8. Acura MDX: East Liberty, Ohio and Marysville, Ohio
9. Honda Ridgeline: Lincoln, Alabama
10. Acura RDX: East Liberty, Ohio