Do i need a passport to fly out of McCarran airport

For domestic flights, you are not required to have a passport to fly until October 2020, which is when the REAL ID Act goes into effect. Once in effect, you will be required to present a valid REAL ID or a Passport to fly on domestic flights. For all international flights, you are required to have a valid passport.

If you don't belong to USA. Then, you have to present your passport at the time of boarding pass check just before security check. It's better to carry it with you all the time.

Thank you, I didn't know about the charges to the law in 2020.