Though only 1 in 10 people in the U.S. claim Irish heritage, many Americans borrow from the Irish on Saint Patrick's Day, dressing up in green, drinking Guinness and celebrating the gorgeous and proud nation of Ireland.

Saint Patrick's Day originated as a religious holiday – honoring Saint Patrick, who introduced Christianity to Ireland in the 5th century – but it has evolved into a celebration of all things Ireland. In 1991, Congress designated March as Irish American Heritage month, but celebrations of Saint Patrick's Day date back to the 1600s.

Here's a look at how many people in the U.S. have ties to the Emerald Isle and where they have resettled since their ancestors arrived in America.

Irish in America

The U.S. Census Bureau collects data on reported heritage of the population. Here is what we know about Americans with reported Irish ancestry:

States with Irish American populations

The states with the highest rate of Irish American citizens are clustered in New England.

New Hampshire, Massachusetts, Vermont and Rhode Island had the highest rates of residents claiming Irish ancestry, according to the Census Bureau. About 1 in 5 people living in New Hampshire tie their roots to Ireland.

Mississippi, South Dakota, Alaska, Wyoming and North Dakota did not report the number of residents with Irish heritage.

Which US county has the largest Irish population?

Honoring Irish heritage on Saint Patrick's Day

The first known Saint Patrick's Day celebration in America took place in the Spanish colony of present-day St. Augustine, Florida. Spanish colonial records mentioned a celebration for Saint Patrick in 1600, and the first known Saint Patrick’s Day parade was on March 17, 1601.

As Irish patriotism in the U.S. grew, annual parades of bagpipes, drums and dancing became the norm. In 1848, several New York Irish Aid societies united their celebrations to form one official New York City Saint Patrick’s Day Parade.

Saint Patrick's legacy grew in the U.S., particularly in areas with large groups of Irish immigrants, such as Chicago, Boston and of course New York.

Contributing: Clare Mulroy