I am sure this has been answered somewhere, but I couldn't find it.

Yesterday, was flying from Florida to ORD and flight was delayed many hours.

I went to the American gate flying to chicago and they could accommodate me.

I offered to pay the one way and they said don't do that, because United should move me to the flight because of the delay, its the rule. Called united - but they said the flight was closed, so I quickly paid and went on my way.

SO in what situations does united have to move you to another carrier during a delay?

Thanks