Earlier this month, I went to the Winnipeg airport to fly home. One sign of a good vacation, for me at least, is that I’m so relaxed at the end that I forget to check carefully what time my flight leaves. I did that this year. For some reason, I had etched in my mind the idea that my flight from Winnipeg to Denver left at 4:30 p.m. So I took one last somewhat leisurely visit with my friend and mentor, Clancy Smith. At about 2:10 p.m., I left his house to stop at a drug store to find chocolate bars that I have trouble finding in the United States. I dropped off my car at the Winnipeg airport and got to the United kiosk just shy of 2:55 p.m. Lots of time, I thought.

Surprisingly, though, there was no one else ahead of me in the United line. When I went to the front of the line to check my suitcase, the United employee tried to do so on the computer but was stymied. He made a quick call in which he asked another United employee to unlock the baggage check. A few seconds later, he printed out a baggage tag. He explained that the U.S. customs and immigration people don’t like people checking in when there is less an hour to go and I was checking in with 57 minutes to go. (When you fly out of Canada to the United States, you go through pre-clearance; when you go through U.S. customs and immigration, you are legally on U.S. soil and, indeed, once you’re through, you see a sign saying “Welcome to the United States.”)

“57 minutes to go,” I thought. I had thought I had over an hour and a half. But it turns out that my flight was to leave at 3:55, not 4:30. When I got to Canada’s equivalent of TSA, I told an employee that I had TSA-Pre, showing him that designation on my ticket. He laughed and said that that wasn’t recognized there.

Not to worry. There were only 8 people in front of me. But 3 minutes later, there were 7 people in front of me. Canada’s “TSA” was moving very slowly. I figured that once I got through, U.S. Customs would go quickly. (On this last, I was right.)

So I thought on the margin. There’s a dishonorable way to get further up in the line and that is to ask someone near the front if you can go ahead of him or her. That way, you impose costs not just on him but also on everyone behind him who was previously ahead of you.

There’s also an honorable way. That is to ask the person directly in front and ask if you can switch places with him. That way, the person who makes the decision is bearing the whole cost. I went with the honorable way. My plan was to do this with as many places I could before someone said no. I explained to the man in front that I had less than an hour before my flight left and asked him how much time he had before his flight. He said he had about 2 hours. So I asked him if he would switch. He looked kind of incredulous, as if my request were unfathomable. Then he said, “Forget it; you won’t make your flight anyway.” I answered, “I might or I might not, but if we switch, my odds improve a little.” He agreed and let me switch. The person in front of him heard all this and, with a twinkle in his eye, let me switch. So did the person in front of him. So within 1 minute I had moved 3 spaces up. By that point, there were only 3 or 4 people in front of me. One was a flight attendant who wouldn’t let me switch. Later I saw her on my flight; she was the only flight attendant on the flight and I could tell by the faltering way she read the directions from her cell phone that she was pretty new on the job. It made sense that she didn’t want to risk being late.

Thinking on the margin can be pretty powerful.

Oh, and I made my flight. The boarding didn’t start until about 10 minutes after I got to the gate.