You have very unusual experiences. Employment contracts are very rare in the US. Offer letters are not contracts. Under certain situations they may be construed

You have very unusual experiences. Employment contracts are very rare in the US. Offer letters are not contracts. Under certain situations they may be construed as contracts, but most companies go to great lengths to avoid this situation. See https://corporate.findlaw.com/human-resources/offer-letters.html https://corporate.findlaw.com/human-resources/offer-letters.... for some guidance on how to avoid writing an offer letter that could be construed as a contract.