Across the country, hundreds of new citizens of the United States of America were sworn in during naturalization ceremonies.

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More than 500 people were naturalized at the Seattle Center alone.

Flags waved in the air at Fisher Pavilion throughout the July 4th ceremony. U.S. Circuit Court Judge Richard C. Tallman, Seattle Mayor Ed Murray and Gov. Jay Inslee attended the event, welcoming the new citizens.

To become a U.S. citizen, people must meet eligibility requirements and go through the naturalization process. One of the requirements is taking the United States Naturalization test. Here are three of the questions on that test:

1. When was the Declaration of Independence adopted? 

2. In what document is the Freedom of Speech found? 

3. What do the stars on the U.S. flag represent?

On Tuesday, people from nearly 70 countries took the Oath of Allegiance at Seattle's event, which is the largest daytime Independence Day observance in the Northwest.

In total, 65 naturalization ceremonies took place across the country and 15,000 people became Americans, WSOC-TV reported.

Richard Adameni, one of 25 people who was naturalized Tuesday in Charlotte, North Carolina, said becoming a U.S. citizen was one of the happiest days of his life.

"It's a big day for me," Adameni, who was born in Jordan, told WSOC. "My heart is American, but I wasn't a citizen."

John Paul, of WSOC-TV, contributed to this report.