Thursday was Flag Day as well as the 243rd birthday of the U.S. Army.

At noon in downtown Cleveland, 30 people representing 18 countries became citizens of the United States. But what does it take to go through the process?

90% of naturalized citizens have a permanent residence card, or green card. You can only apply for citizenship after five years of residents, or 3 if you are married.

The law requires new citizens read, write, and speak basic English. They also need to have a basic knowledge of U.S. history and government.

Shu-How Lee is originally from China, but has been studying mechanical engineering at Cleveland State for more than six years. The application is quite detailed and costs $800 to file.

"The forms you have to fill out include your background, your history, all of your experiences, plus your address and education within the United States," Lee explains.

Eligible applicants are fingerprinted and go through a background check before they wait for approval.

While some of the new citizens, like Norma Atkinson, waited four years for their application process to be complete, Shu-How's process was complete in two months. It's quite a detailed process and has different requirements for different situations.

Learn more by going to the US Citizenship and Immigration services website.

WATCH | See the swearing in of 30 new United States citizens below: