MOBILE, Ala. — It was here, some 16 months ago, that Donald J. Trump displayed the sheer power behind his candidacy, packing this aging gridiron with tens of thousands of fans braving traffic and the August sun to get a glimpse of a candidate who, despite his swelling crowds and soaring poll numbers, was still being dismissed as a long shot.

So he returned on Saturday, as president-elect, to the place that launched, if nothing else, his own team’s confidence in Mr. Trump’s chances, to a crowd smaller in size but no less energized, to say one last “thank you” as only he can: through boasts and promises, threats and pledges, each met with a whoop from the crowd.

“We are really the people that love this country,” Mr. Trump told the crowd, adding that this was a part of his “little victory tour, but really they were thank you tours.”

Mr. Trump spent the majority of his time focusing on his victory. For more than half of his roughly hourlong speech, Mr. Trump recounted blow-by-blow the tale of his victory, a pared-down version of his stump speech that featured mockery and impressions of the news media, rhetorical questions and the occasional dig at the confidence of the Hillary Clinton campaign heading into Election Day. At the end of the night, he joked that he offered to buy the Clinton campaign’s fireworks “for five cents on the dollar.”