American Idol Season 12 Winner Candice Glover (C) is seen onstage during Fox's "American Idol 2013" Finale Results Show at Nokia Theatre L.A. (Kevin Winter/GETTY IMAGES)

It’s our most American holiday, so it’s only natural that we want to see our most American stars — the ones we voted for on television.

No, it’s not just your imagination: A steady stream of reality TV contestants have infiltrated the ranks of talent appearing in the annual PBS fireworks show “A Capitol Fourth,” a three-decade-old tradition that plays out on the West Lawn of the U.S. Capitol and is broadcast across the country.

For a special that started with singer Pearl Bailey and conductor Mstislav Rostroprovich in 1981, it might seem strange that on this year’s show, two “American Idol” winners are mixed in onstage with Neil Diamond and Barry Manilow. But musical shows have exploded on television in recent years, so it makes sense to recruit those stars for this spectacle of Americana — while PBS gets a nice ratings bump, because the talent comes from some of the most-watched series on television.

Reality-show singers have been part of the broadcast for several years, but on Thursday, the lineup has a record number of TV crooners, both from reality and scripted series. This includes “Idol” champs Candice Glover and Scotty McCreery, along with “America’s Got Talent” prodigy Jackie Evancho. On the scripted side, there’s Darren Criss, who plays the dreamy Blaine from Fox’s “Glee,” and Megan Hilty, the Marilyn Monroe wannabe on NBC’s “Smash.” Plus Tom Bergeron, the host of ABC’s unstoppable dance competition “Dancing With the Stars.”

“Today, these [TV stars] are so popular. You’re able to have a real connection with them as amateurs-turned-stars,” said Michael Colbert, who has produced the Fourth of July special for more than 20 years with his father, executive producer Jerry Colbert, the man who founded “A Capitol Fourth.” “People really love it . . . and one of our goals is to try to get something for everybody.”

From its film debut in 1947 to being sung on the Capitol steps on September 11th, 2001, “God Bless America” has served as a patriotic symbol throughout American history. (Nicki DeMarco/The Washington Post)

Indeed, years past featured an eclectic mix of music genres, including Roberta Flack and Marvin Hamlisch (1987); Lee Ann Womack and Ray Charles (2000); Dolly Parton and Kristin Chenoweth (2003); Stevie Wonder, JoJo and Jo Dee Messina (2006).

It was around 2004 that reality TV started to creep in, with “Idol” runner-up Clay Aiken. Since then, there has been an “Idol” finalist on stage nearly every year, including David Archuleta, Taylor Hicks, Jordin Sparks and Phillip Phillips.

Other reality show stalwarts started showing up too, from Il Divo (familiar to viewers of Britain’s “X Factor” and “American Idol”) in 2005 to Javier Colon (of NBC’s “The Voice”) last year. “Glee” stars (Matthew Morrison in 2011, Amber Riley last year) have also joined the lineup.

Having faces from some of the country’s most-watched shows certainly doesn’t hurt the special’s numbers. “A Capitol Fourth” has steadily expanded its audience, and the 2012 show attracted 6.3 million viewers (coming in behind NBC’s Macy’s fireworks special, but beating CBS’s Boston Pops spectacular), making it one of PBS’s biggest programs of the year.

Colbert agrees that the popularity of the actors and reality show contestants keeps viewers tuning in, especially because those stars are on television every night. “Having people that people know and like makes it a bigger draw,” he said.

So who, in fact, are big draws?

At the Wednesday rehearsal for the show, it was Evancho. McCreery. A few who had made the trek to the West Lawn of the Capitol to secure good seats were thrilled that Glover had won this past season’s “Idol.” But as far as the TV star with the most diehard fans?

“Darren Criss,” said Samantha Kline, Jessy Kline and Bryna Steele simultaneously. The Walt Whitman High School students traveled from Bethesda to the District on Wednesday afternoon to see the “Glee” actor.

“He tweeted about it,” Samantha, 16, said.

“We get his tweets sent to our phones,” Bryna, 15, added.

About 50 people arrived at the West Lawn, armed with food, blankets, chairs and thick novels, nearly five hours before the full concert dress rehearsal started at 8 p.m. Some have been coming to the show for years and remembered the days before the TV stars took over the broadcast.

Tracey Taylor of Leesburg, Ohio, who used to live in the area, recalled when opera singers populated the annual show. But, she acknowledged of the reality TV contestants, “they’re names people recognize these days,” which makes it a great way for the PBS broadcast to get more exposure.

For the non-reality-show viewers, there are still other offerings. John Williams will conduct music from the score of “Lincoln” (with Steven Spielberg on hand for a video introduction) with the National Symphony Orchestra, directed by Jack Everly. Neil Diamond will perform the national debut of “Freedom Song (They’ll Never Take Us Down),” a tribute to victims of the Boston Marathon bombings.

And, amid the patriotism, somber tributes and TV stars, there will be Barry Manilow, who was holding his own as a draw at the Wednesday rehearsal.

Sighed Marlene Koenig of Alexandria: “If Barry Manilow wasn’t here, there’s no way I would be here this early.”

A Capitol Fourth

(90 minutes) airs 8 p.m. Thursday
on WETA and MPT.