In the parking lot across from the terminal. There should be someone on duty to check it.
Have an early flight before the normal hours, do I just leave the keys in the car
It's not across from the terminal. It's at the end of the terminal. If no one is at the booth for your rental brand, you can usually leave the keys with a competitor or drop them in a box at the kiosk inside near baggage claim.
The same place you picked it up for me it was... PIE Airport
There's a parking lot across from the terminal - it's for the rental cars only. One large lot is shared by Alamo, Enterprise, etc. Follow the signs on the way in for rental car return. You pull into the lot and look for the Alamo designated spots. Park and the attendants come right over and check the car back in as you're pulling your luggage/belongings out. They give you a recy on site too. Very quick and easy!
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