On Monday morning, in a federal building in West Philadelphia, 51 people from 32 countries took the oath to become naturalized U.S. citizens.

They raised their hands and swore to renounce allegiance to any "foreign prince or potentate," to take up arms if required to defend America, and to attest they took on these obligations freely "without any mental reservation."

Many of them became citizens in order to find work and to vote.

"I think for many people, being able to apply for a federal job, and being able to vote are big reasons to become a citizen," said Jane Cowley, spokeswoman for the regional office of U.S. Citizenship and Immigration Services. "But once you become a citizen through this naturalization process, you have all the rights and responsibilities all natural-born citizens have — other than being able to run for president."

Since October, 609,251 people have become American citizens, an uptick over the previous fiscal year. There was an increase in 2007, ahead of President Obama's first presidential win. However, numbers vary widely year to year, and the reasons why people choose to become citizens are not recorded. Cowley said she cannot directly tie citizenship increases to election cycles.

Nevertheless, some people are clearly inspired to becoming naturalized in order to vote.

One of those new Americans is Simon Firth, a native of Staffordshire, England. A mechanic and bike-frame builder, he has been living and working in Philadelphia for 22 years. During that time he met and married his wife, Vicky, a Philadelphia native.

She was there during the Monday ceremony. "Tears were welling up, but I pushed them down," she said with a laugh.

Together they celebrated his citizenship with breakfast at the Down Home Diner at the Reading Terminal Market.

"What is more American than a diner?" said Firth, tucking into home fries and coffee. "A diner is American."

He arrived in the States in 1994 with no plan. He started squatting with bike messengers in San Francisco, liked it, and never left.

"My status in America was not on solid ground at that point," Firth admitted. "We got married and applied for a green card. Took two years to get that. We've been married for 18 years. We bought three houses, started a business. It was time to get involved in the political system."

Firth started thinking about becoming a citizen because, as a small-business owner, he wants a say in local elections. "Taxation without representation," he said. "I've paid a lot of taxes, and not been represented well."

The upcoming national election cinched the deal.

"If I'm gonna vote, this is the one," said Firth. "Watching on the sidelines has been upsetting. In England, as soon as I turned 18, I would vote on everything. I didn't vote for Margaret Thatcher ... if that's not a way to indicate which way I'll vote this time, I don't know."

For two decades, Firth has not been able to vote anywhere. He had to sit on the sidelines and watch as England voted to pull out of the European Union during the recent Brexit. Surprised and dismayed at that result, he wanted to be sure to be part of the next big decision in American politics.

He also wanted to feel attached to his chosen country because, for the last 22 years, he has been finding alternative ways to exercise citizenship.

"Simply by riding my bike, signing a petition, showing up at community meetings. Just cleaning the street outside my shop and my house — that's part of being a good citizen," said Firth. "This is the next step of being a good citizen."