How early can you check in for a flight?

I have a flight in december out of Portland Airport around 730 in the morning. I live in Eugene and don't have a car. there isn't a shuttle service that will get me to PDX in time for my flight in the morning, so i would have to get up the night before. if i were to get in the night before, could i sleep in the airport at the gate? i don't have the money for a ride up and a hotel.|||Looks like it's an international airport that operates 24/7, therefore it's okay to sleep in the airport as long as the security people know that you're going out early next morning. If you have an e-ticket for a domestic flight, you should be able to check-in online 24 hours before departure. Otherwise at the airport usually you can check in 2-1/2 hours before departure.|||You can probably check in the night before. Call the airline to find out how early they allow check-ins.|||Looks like sleeping there is OK


http://www.sleepinginairports.net/usa/po鈥?/a>