posted on US board, probably better here: have a 6:10 a.m. flight on a Sunday in July from Newark - what time do we need to get there for check in?? Thanks.

If a Domestic flight than by 5am, if Int'l it should be 2-hrs. prior, but I'd check with airlines either way to be sure that the reservation/check-in agent desks are open.
I've gotten to airports for early flights and have found no agents on duty!

Unless you were going somewhere pretty exotic and had to go through passport control etc, I'd say if you were there by 5:30am you'd be ok. Domestic US Air (from Term A) is pretty small, and at that time of the morning I doubt if the security line will be much of a problem.
The airport itself should be a breeze as well.

Disagree with mauld, because at EWR it can take some time to get from check in, through security and to your gate, and 35 minutes is REALLY cutting it close. Airlines are also enforcing their check in time rules. Best bet is to check with the airline and follow what they advise.

Actually, we are flying EWR-Vancouver (via Detroit) - we live in Washington State. With other feedback, am figuring two hours. At the airport at 4:10??? how do you find out if they even have gate agents there at that hour of the morning? Call the airline, or the airport itself? Thanks.

Call your air carrier to find out what time the agents come on duty. They'll probably give you an early hour, but if you're flying via Detroit you won't be on a large plane with lots of passengers. However, I'm sure yours won't be the only early flight.

Call your air carrier!