Is there a way to know if a company is legally required to pay overtime?

I start work for a new company in a couple of weeks (a small tree care company) I have been told that long hours will be a regular part of the job in peak seasons, but I stupidly didn't think to ask if they pay overtime. That'd be kinda nice to know. They are very good at answering questions from me, but we've been back and forth several time with questions I've had for them and I don't want to wear out their patience with me. I'm not familiar with the laws surrounding this sort of thing (I am assuming there are some!) Is there a way to determine if a particular employer is legally required to pay their employees overtime?

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