I am travelling and have to change planes in Minneapolis

I am travelling and have to change planes in Minneapolis?
We are flying Northwest both flights. Cleveland to Minneapolis and Minneapolis to Calgary. What happens if the flight from Cleveland is late departing and we arrive at the airport after the other flight is scheduled to leave. Do they have a record that people are on a late flight and need to board? Will they wait? There is supposed to be an hour layover, but today I was just checking out our flight info online and the plane out of Cleveland left one hour late and didn't arrive until after the connecting flight (for us) left. The 2nd plane left at its correct time. If this happens on the day we fly, which is in a couple weeks, what happens? ( and I know I am probably freaking out over nothing, but ...) I have only flown 2 times before and never had a layover. Anyone out there had this happen to them? We are going on a ski trip with a ski club, so I had no control over the scheduling.
Air Travel - 2 Answers
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1 :
They do not hold the flight. Once you get to MSP you go to the counter and they will book you on the next flight with available seating.
2 :
No they will not wait. If it becomes obvious your Cleveland flight will be very late, do not get on that flight and hope for a miracle. Go to the gate agent and ask to be rerouted (possibly via Detroit), or be confirmed on the next Calgary flight.