Mystic ― As Sunday’s Mystic Irish Parade kicked off at 1 p.m., many thousands were sitting or standing on the sidewalk or along the drawbridge to watch the parade procession.

Meanwhile, inside bars and restaurants behind them, workers were getting ready for the second rush of customers that would crowd their businesses after the parade concluded.

“It’ll be mayhem in here soon,” said Nick Georgetti, general manager of the Engine Room, a Stonington restaurant that usually serves American fare.

The restaurant had for the occasion transformed its menu into one that included corned beef hush puppies, corned beef sandwiches and burgers, all of which were served in a “grab-and-go” style that allowed paradegoers to grab their food quickly and leave, or if they wanted to, stand and warm up while they ate.

“It was a slow start today, but I think the cold is keeping people in,” said Nick Allyn, who was working the door at the restaurant.

Moments before the parade started on Route 27 near Mystic Seaport, Allyn greeted people as they came in for a bite to eat or grab a beer.

“The parade will start in 15 minutes,” he said, checking his watch. “And then the rush (will come) after that.”

“Everybody has the green Bud Lights for today, and an extra keg of Guinness,” Allyn said of the preparations the Engine Room and other local restaurants and bars had been making prior to the parade.

His words echoed those of Maggie Lanphere, a bartender at the Harp and Hound Irish tavern at 4 Pearl St. in Mystic.

“We just gotta stock the hell up with green Bud Lights,” she said three days before the parade. “We’re ready for it, we’ve been doing it for a while.”

The tavern, owned by parade organizer Leo Roche, is always packed on parade day with little room to move inside, she said. Both the Engine Room and Harp and Hound had taken out most of their seating in advance. Come Sunday, Lanphere’s prophecy of a packed bar had rung true.

“It’s really, really busy,” fellow bartender Alan Sheehan said around noon. “We’re selling a keg of Guinness every 20 minutes.”

Behind the counter, Sheehan, who had dragged a full keg toward the bar, immediately turned his attention to a green-clad customer’s request for a Coors light and a vodka soda as another bartender got to work on a request for 18 more. Other customers tried to find space at the bar to place their orders.

In the corner of the tavern, as the Dropkick Murphy’s “I’m Shipping up to Boston” blasted over a large crowd’s conversation and laughter, a man handed Liam Costa, of Pawcatuck, a shot of brown liquor. He didn’t know what it was, but after smelling it, decided it was Jameson Irish Whiskey. His parents, Tom and Pam, each had a Guinness in hand.

The family, annual paradegoers who always enjoy the event’s friendly and family-oriented atmosphere, would be going to the Mariner at 21 W. Main St. after for a few more drinks.

“We all kind of start here and we’ll mosey out,” Pam Costa said.

At Chapter One Food + Drink, a restaurant at 32 W. Main St., security guard Richard Husar and server Miranda Chesnut were serving $3 hot dogs and Styrofoam cups of “Irish Chowder,” a stew made of Guinness, potatoes and corned beef.

About a half-hour before the parade had began, Husar said they’d probably served about seven customers through an open window of the restaurant, transformed into a pick-up window.

“Plus inside, you’re probably looking at about 20 or so,” he added. “We’ve still got only a few people walking around right now, so it will get busier.”

At a main bar area in the next room, more than 50 people were already celebrating. Seated in a nearby booth behind a cart serving beer on ice, Stonington resident Haley Powers had just finished her cup of chowder.

“It was wonderful,” she said. “Very flavorful.”

Powers watched the parade through the window to keep out of the wind.

d.drainville@theday.com