“Jared is particularly interesting because it shows where America has come to,” he said, “and that America is a much, much more tolerant place than it was.”

That shift may resonate most strongly with those who have known the country as it was.

For Mr. Miller, who grew up in Colorado’s more conservative, red-leaning Western Slope, the election of a gay governor was all the more satisfying for being in his own state. “For me, on election night, seeing Jared and Marlon up on that stage and him giving his victory speech — I so much would have loved to have known what that would have felt like back when I was in high school,” he said.

This rang true even for young local voters, who in the week leading up to the inauguration described feeling elated. Jean Peterson, a paralegal in Denver who turns 26 this week, described watching Mr. Polis’s November victory speech with her girlfriend, tears in her eyes.

“It was really moving,” she said, “to see him point to his partner and all the support that his partner gave him, to have someone acknowledge their partner … We were both kind of crying.”

At his inauguration on Tuesday, the Denver Gay Men’s Chorus warmed up with “True Colors” (Cyndi Lauper, who first recorded it, was booked for the inaugural ball that night) before remarks from local grandees and faith leaders and the new officials were sworn in. Mr. Polis sat with Mr. Reis and their children behind a pane of bulletproof glass, a precaution one veteran Colorado reporter noted he hadn’t seen in five previous inaugurations. But when Mr. Polis got up to speak — after a quick selfie with the crowd — he addressed divisiveness and diversity only briefly.