Are industries unionized or just companies?

Say I want to start a new airline. Right from the start are my new employees automatically a part of a relevant union (pilots, stewards, etc.) or does a union have to come in and get my new employees to agree to membership?

Also, if a particular company is unionized (or at least a soecific part of their laborforce) do I, as a new employee, automatically have to join the union or can I opt out if I so choose? A flipside to this may be that I personally don’t have to be a member of a particular union but the company is obliged to hire only union workers.

FWIW this is not a great debate about whether unions are a good or a bad thing.

Your employees aren’t part of the union until they actually join the union.

Industries are not automatically unionized nor are companies. Alot depends on your state laws, industry being organized (there is a big difference between organizing let us say auto workers and farm workers, federal laws have different laws for labor organizing), and what contract was signed between company and union. In your example, depending which state you are talking about, the union would have to organize in order to get membership and get a contract. It’s not automatic.

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Again, it depends on the contract that both parties signed to and what are the laws of the state.

XicanoreX