St. Patrick’s Day is celebrated on March 17, his religious feast day and the anniversary of his death in the fifth century. Legend has it that this patron saint had given a sermon from a hilltop that drove all the snakes from Ireland. He also used the three-leafed shamrock to represent the Trinity how the Father, the Son, and the Holy Spirit could all exist as separate elements of the same entity—and converted the pagans to Christianity. The Irish have observed this day as a religious holiday for hundreds of years. People wear green in memory of the Emerald Isle and wear shamrocks.

The first St. Patrick’s Day parade, however, took place not in Ireland, but in the United States. Irish soldiers serving in the English military marched through New York City on March 17, 1762. Along with their music, the parade helped the soldiers, as well as fellow Irishmen serving in the English army, to reconnect with their Irish roots.

Over the next thirty-five years, Irish patriotism among American immigrants flourished, prompting the rise of so-called "Irish Aid" societies, like the Friendly Sons of Saint Patrick and the Hibernian Society. Each group would hold annual parades featuring bagpipes (which actually first became popular in the Scottish and English armies) and drums.

Up until the mid-nineteenth century, most Irish immigrants in America were members of the Protestant middle class. When the Great Potato Famine hit Ireland in 1845, close to a million poor, uneducated, Catholic Irish began to pour into America to escape starvation. Despised for their religious beliefs and funny accents by the American Protestant majority, the immigrants had trouble finding even menial jobs. When Irish Americans in the country’s cities took to the streets on St. Patrick’s Day to celebrate their heritage, newspapers portrayed them in cartoons as drunk, violent monkeys.

However, the Irish soon began to realize that their great numbers endowed them with a political power that had yet to be exploited. They started to organize, and their voting block, known as the "green machine," became an important swing vote for political hopefuls. Suddenly, annual St. Patrick’s Day parades became a show of strength for Irish Americans, as well as a must-attend event for a slew of political candidates. In 1948, President Truman attended New York City’s St. Patrick’s Day parade, a proud moment for the many Irish whose ancestors had to fight stereotypes and racial prejudice to find acceptance in America.

"The Emerald Isle" probably refers to ().

A. Ireland

B. England

C. Scotland

D. New York City