Geaghans Pub and craft brewery got the party started early Saturday with people lined up outside before the doors even opened.
Owner and general manager Larry Geaghan said, "I'm always amazed when we open the door the crowd that's ready to come in I think we had like 50 people waiting at the door."
He said it's nice seeing familiar faces come in and celebrate. "One of the most fun parts is that we see folks that know other folks that are going to be here and they reunited and they come in from all over the country really."
The party will continue all day Saturday.
"We've got bad pipers coming in we've got some musicians playing traditionalized Irish tunes. It's just a fun time" said Geaghan.
Although it's a day full of drinking and eating. Officers say they are quite busy this time of year.
Seargent Wade Better of the Bangor police department said, "Busier during the evening hours. We encourage anybody who's gonna go out tonight to basically plan ahead have a plan that in case you have to much to drink you have someone to get you home safely."
He said they'll have officers out all night long. "We'll be looking for impaired drivers encourage you not to risk driving when you've had too much to drink because there's a very good chance we're gonna get you off the road tonight."