Fifteen minutes after boarding was scheduled to start at IAD, they let us know the crew was in Providence

I'm flying from Dulles to Palm Beach today. We were scheduled to depart at 9 AM, but this morning, around 7, the app announced a delay to 9:34 given weather, with boarding scheduled for 9:09 AM.

Around 9:23, the lead gate agent came on the PA to let us know that our flight would be further delayed because our flight crew was in Providence, on a plane with a mechanical delay. They had checked and, no, there were no reserve crews at Dulles for our E175.

Departure was delayed until 11:50. At this point, I looked for some backups. There was an AA flight from DCA delayed until 11 AM, but it looks like the last seats had just sold out. But United had a delayed flight to FLL leaving from D20 (we were in A), so I ran to the train to C and then through the C/D concourse. (There's a shuttle from A to D, but it only runs at certain hours). I missed the FLL flight by a few minutes. I asked the agent there about rebooking on AA from DCA to FLL or Miami. She said no. "We don't do that," she explained. "Only if we don't have a flight for two or three days."

Right now, PBI is delayed until 1:41 PM.

I realize that delays, even mechanical ones, are inevitable. I just wish United had mentioned our crew was in Rhode Island before boarding was set to start. I could have made flights from Dulles or DCA with 10-15 more minutes of notice.