Hey road trip, Antifreeze and water doesn't evaporate quickly. It's super easy to get the car on plastic ramps or jack-stands and find the "little bugger" source of the leak. As the car gets warm while driving, the cooling system builds pressure. Additional heat is caused when the air conditioning system is turned on. The standard radiator pressure cap is rated @15-16 pounds. Until you get the leak fixed go to Carquest and purchase a 4 or 8 pound pressure cap for the radiator so that the cooling system doesn't build as much pressure forcing the coolant out the leak. Install the cap when the car's motor is stone cold.
If you don't have the time or equipment to find the leak yourself, take the car to any auto service shop and request a *Cooling System Pressure Test. The leak will appear in seconds and necessary repairs can be made.
The leak could be a radiator or heater core hose, radiator end tank O ring, radiator core, loose hose clamps, heater core or another water-pump.
