St. Patrick's Day: How the U.S. celebration compares to Ireland's

Flashback: St. Patrick's Day has been celebrated in the U.S. by Irish immigrants since the 18th century.

Here are some similarities and differences between America's and Ireland's St. Paddy's Day, explained by O'Callaghan, who now lives in New York.

In Ireland, it's a national holiday, which means schools, banks and most businesses are closed.

• "It's always a day off or a long weekend. A lot of people will go on holidays and see what other countries are doing for St. Patrick's Day."

In Ireland, drinks mixed with Irish whiskey are more popular than green beer.

• "I always started the day with an Irish coffee."
• "In the town of Tullamore, they serve Tullamore D.E.W. whiskey with apple juice. They call it the tapple dew."

In the U.S., we pinch those who don't wear green.

• "That's something I didn't know about until I came [to the U.S.] It's definitely a U.S. thing that I hadn't been familiar with at all."

In the U.S., we dye rivers green.

• "It doesn't happen in Ireland. We grew up watching Chicago every year, like it was such a spectacle. I got to go last year for the first time ever and it was amazing."

Both countries celebrate in their local communities.

• "There's always a local parade, which is always a great source of entertainment. It's always a great collection of celebrating community and that's really a big part of what St. Patrick's Day is."