When flying, mention to your travel agent that you're using a walker or wheelchair and need extra time to board the plane. DON'T BE SHY! I've actually worked in airports pushing wheelchairs from the ticket counters to the gates and to baggage claim or their cars in the parking lot.
In SOME airports, like Milwaukee or Philadelphia, that distance can be a VERY LONG WALK. In Milwaukee, for example, from the gates to baggage claim, its all UPHILL. You're not allowed to take walkers, scooters, or wheelchairs on moving sidewalks in ANY US airport.
I've walked past people who were about to have a coronary because they chose to make the walk rather than be escorted. Yes, the pushers work on tips, and they greatly appreciate it, but every once in a while, I didn't mind helping somebody out because Karma usually comes back with a big tipper later on, so it balances out.
When you're going through Transportation Security Administration (TSA) Screening: