Originally Posted by
chinatraderjmr
I was told they are considered the same city (NYC) for purposes of routing, SDC, etc. of course, this means nothing as I was told this by an agent who allowed me to change flights from ORD-EWR to ORD-LGA
Definitely not. EWR is carved out from a routing rules perspective to allow UA to charge a huge premium for its routes from there.
You probably had an agent who was from the UA subsidiary and assumed it was treated as NYC.