Lori Umbrino saw her first Billy Joel concert at Shea Stadium in Queens in 1990. More than three decades later, she stood with her two children outside Madison Square Garden on Thursday evening, each wearing a T-shirt from the singer’s concerts across the years.

“We’ve been there with him along the journey,” said Ms. Umbrino, 51, whose shirt was from Mr. Joel’s 100th concert at Madison Square Garden on July 18, 2018, designated Billy Joel Day in New York State.

That journey has led them back to Madison Square Garden, where Mr. Joel was performing the 150th and final show of his 10-year residency there.

The milestone — and, for some, the devastating misunderstanding that Mr. Joel was retiring — drew veterans of his shows, first-timers, families and singles from around the city and the country. Thousands of people piled into the Garden to hear Mr. Joel glide from hit to hit.

Stuart Stephenson sat outside the arena at 34th Street and Eighth Avenue, blowing into his melodica, fingering the keys to play “New York State of Mind” and “Uptown Girl.” Fans and commuters streamed by, hawkers sold T-concert shirts, and drivers planted their hands on their horns.

Mr. Stephenson saw a news segment on Thursday morning about Mr. Joel’s concert, and thinking the Piano Man was closing his Steinway for good, he rushed into Midtown.