WORCESTER – For many of the Irish pubs and restaurants in the city, St. Patrick’s Day is the busiest day of the year, when ordering extra kegs of Guinness and loads of corned beef is a must.

Throw in that the holiday is falling on a Saturday this year with the traditional Worcester County St. Patrick’s Parade set for the Sunday preceding it on March 11, and restaurant owners are preparing for thousands of revelers in a week-long celebration of everything Irish.

The saying goes that we are all Irish on St. Patrick's Day, but many of the owners of Irish businesses in the city are of Irish heritage and live it 365 days a year.

Brendan D. O’Connor, 62, and his wife, Claire A. O’Connor, who own O'Connor’s Restaurant & Bar on West Boylston Street, are straight out of a small village located in the middle of Ireland.

The couple owned and operated a waterside hotel, the Lough Derg House and The Lake Café, in the village of Dromineer on the shores of Lough Derg, a huge “Winnipesauke-style” lake, Mr. O’Connor said, until coming to the U.S. in 1988 when he was 32.

“Those were tough years in Ireland with 25 percent unemployment,” Mr. O’Connor said with an Irish accent while taking a break from ordering spirits and boiling corned beef at the restaurant. “Everybody was hungry and thirsty and there was mass immigration.”

He said they came to the U.S. to make a better life and develop a business they believed there was a demand for, choosing Worcester because they discovered it had the highest Irish concentration in the country at the time with 39 percent of people claiming Irish heritage. They bought a small existing “burned out biker bar,” he said, with 75 seats and renovated and expanding it to 375 seats. The family-owned business open 30 years has enjoyed popularity and success in the area since.

The busiest day of the year, Mr. O’Connor said, is St. Patrick’s Day, when they double the business they typically do on their busiest Saturday night.

“It is the high holy day and the busiest day of the year,” he said. “It is a day of celebration of all things Irish and a celebration of heritage more than anything. It makes us forget turbulent times and gives us a heightened sense of who we are and what we came from.”

The restaurant is on the route of the St. Patrick’s Parade, he said, that attracts more than 50,000 spectators with around 1,500 runners participating in a road race afterward along the route.

To prepare for the influx of customers following the parade and on the holiday, the O’Connors hire extra help, order thousands of pounds of corn beef and stock up on Irish whiskey and beer.

“We’ll be boiling corned beef 24 hours leading up to parade. People just have a hankering for it,” he said. “It is on the menu every Thursday night and sometimes during Christmas, we can’t even get it. We call it the Thursday night Irish bachelor special. It is not exactly date night food. Don’t expect a good outcome of that date.”

After 30 years, Mr. O’Connor said they know what to do and what to expect.

“We’re ready for it,” he said. “A few years ago, we had a power outage from 5 to 7 on St. Patrick’s Day when a man hit a pole and knocked out the power. If we can survive a power outage when the place is full, we can handle anything. We joke that no one at the bar knew.”

The European and New England fair restaurant offers a broad range of cuisine.

“It isn’t just corned beef and cabbage anymore,” he said. “It is a sophisticated food market in Ireland now, not just potato and pig and boiled dinner. It has evolved over the years.”

There is also a huge resurgence of whiskey brown spirits, he said, with younger generations looking for whiskey flights. Around 10 years ago, they offered three Irish whiskeys. Now they have more than 50 available along with gin, Guinness, craft beers and this year, a 1794 Series Stout made by Wachusett Brewing Co. by guest brewer Fergal Murray, Guinness’ former head brewer, that is launching over St. Patrick’s Day.

At Fiddler's Green on Temple Street, manager Terrence “TG” O’Connor, whose grandfather came to the U.S from Ireland, is preparing for an estimated 1,000 people to come through the doors after the parade and on the St. Patrick’s Day. They usually have less than 100 customers on a Saturday night, he said.

“It’s a real Irish pub with mahogany wood – a duplicate of what you’d see in Ireland,” he said.

Mr. O’Connor, who also co-owns Vintage Grille on Shrewsbury Street, said he started managing Fiddler's Green in September, though Vintage Grille catered events for the business before that.

He put out a call on his members Facebook page for recruits to help out on what he expects to be the busiest days of the year parade day and the holiday, and order 16 kegs of beer – seven of them Guinness – for parade day alone. That’s a bit more than the pub’s typical three-to-five kegs a week.

The business also has three function halls for rent and Mr. O’Connor plans to open one up to the pub both days. He has also hired live bands to play a mix of music both days, including some Irish tunes.

“There is no question it is going to be a week-long celebration,” he added.

Over at Patsie Dugan's on Millbury Street, the restaurant with the big, green Irish leprechaun hat, owner Patrick A. Patton is also preparing for the business’ busiest day of the year with all his staff scheduled to work.

“Business doubles and triples,” Mr. Patton said. “It is a fun day to work. Everybody has a positive attitude. It is close to the start of spring and the next big day is opening day of the Red Sox. Besides that, I can’t think of another day other than St. Patrick’s Day to look forward to.”

The business serves corned beef March 1-17 in celebration, added to the mulligan stew and blarney sandwich on the menu, and fish and chips for those observing Lent.

With St. Patrick’s Day on Saturday, he said people will pack the place. He plans to play Irish music, because, he jokingly said, live bands tend to get “hammered” after the first few sets.

“When it comes during the week, you see a lot of suits and they don’t go back (to work),” he said. “But, it’s on a Saturday this year and will be busier this year. It’s all hands on deck and everyone has to work.”

Mr. Patton also plans to wear a special pin he has had for 45 years given to him by his mother who came to the U.S. from Achill Island, the largest island off the coast of Ireland.

He said every year as a child, his aunt would mail pins to him and his siblings, with an Irish flag and harp on them and his mother would make them wear the pins to school.

“I hated it,” he said. “And, then I find out what they and the Easter lily were. It was a big I.R.A. (Irish Republican Army) thing and you could get arrested in Ireland for wearing one 100 years ago. I still have mine and wear it one day a year on St. Patrick’s Day.”

For those not of Irish heritage, including his diverse staff and clientele, Mr. Patton said it only takes “$5 and 16 black ounces to get a little Irish in you.”

“Or, you can expedite the process and drink an ounce-and-a half of Guinness,” he said, laughing. “Everyone on our staff is honorary Irish on St. Patrick’s Day, even Dan the bartender, that SOB from Philly and diehard Eagles fan. Even he is a little Irish on St. Patrick’s Day.”