I am looking at a flight from SFO to CAE. And the same ORD-CAE arriving about 2:53 am.

I thought it was an error to ORD to CLT, GSP, ORF, ATL etc all have this 3 am arrival.

When I mentioned it the Agent in CAE, she laughed until she went to check it on the computer.

A few weeks later, different agent came up and engaged in conversation. Seems I was the one who opened the box. The airport is closed at 3 am, so there is a series of conversations with the airport and other services of dealing with a 3 am arrival.

Knowing weather at ORD this time of the year, that 3 am arrival could easily be late, keeping rental car agents, etc. there until the wee hours of the morning.

It appears that UA's scheduling did not communicate with the airports in a timely manner.