Wearing green plaid caps, dozens of dancers hopped, kicked and twirled – all while keeping their arms ramrod-straight at their sides – during the St. Patrick’s Parade on Sunday in Portland.

The dancers from the Stillson School of Irish Dance were part of a cornucopia of Irish images and sounds at the parade, including people dressed as leprechauns, as a glass of beer and as a pot of gold at the end of a rainbow. Several bagpipe bands performed, one green-clad unit after another marching down Commercial Street for the annual parade sponsored by the Irish American Club of Maine. Even characters from the “Ghostbusters” and “Star Wars” movies waved to parade-goers.

“I guess the ‘Ghostbusters’ are Irish. I never knew that,” joked one parade attendee.

Marchers carried numerous Irish flags, including the national flag and other colors and designs denoting Irish heritage, such as one green flag bearing the image of a harp. Like Boston, New York City and other Eastern Seaboard cities, Portland experienced an influx of Irish immigrants in the mid- to late 19th century. About 20 percent of Portland’s population is of Irish heritage, according to the U.S. Census.

But the school-age dancers captured the hearts of many in the crowd, pounding their feet in unison to pulsating Irish music.

Ciara Stillson, 17, of Gorham, the daughter of the Portland school’s founder, Carlene Stillson, said Irish dancing is a great workout and fun to do.

“I really like the dancing because it’s a mix of a bunch of different techniques, like ballet, tap dancing and clogging. It’s super technical and we’re hopping a bunch of times per minute,” Ciara Stillson said.

“It can be really tricky,” said Madeline Downey, 10, of Gorham. “We have a lot of jumps and crossover steps to learn.”

Carlene Stillson said practice during the height of competition season encompasses two to three hours three days per week. She compared the rigorous training to preparing for a boxing match. The Stillson School of Irish Dance was founded 24 years ago, she said, and she’s passing down the Irish dancing tradition she learned from her aunt.

Several dancers from the school will compete March 20-26 at the World Irish Dance Championships in Glasgow, Scotland.

Cate Davis, 8, of West Bath, was most interested in the candy being thrown to the children attending the parade, and seeing Portland Sea Dogs mascot “Slugger” dressed in Irish garb.

But she said she enjoyed the dancers.

“My daddy says I do lots of Irish dancing when I’m running around like crazy at home,” Cate said.

St. Patrick’s Day – March 17 – is Thursday.