IBM: ~400,000 GE: ~300,000 Ford: ~180,000 Apple: ~80,000 Pfizer: ~78,000 DuPont: ~70,000

Additionally, I know that Microsoft almost another 100,000 people employed as "vendors". Furthermore, these are the kinds of stocks that tend to be widely held by e.g. pension funds and 401k programs, so their impact extends well beyond their employees.

Now to be fair, these employee counts are worldwide and not just in the United States -- and the interests of their management are not necessarily aligned with the interests of the employees. But it's important to have some perspective on the scales of things. Historically, Ford has done a lot more to raise the standard of living of the average American than Facebook has.

Disclosure: I work at Microsoft.