Citing concerns for the well-being of children and respect for the democratic process, participants in the national March for Marriage in Washington, D.C., stressed the importance of marriage for society.

Sara Barrios from New York City told CNA that without the biologically-based institution of marriage, the foundations of family and society "will fall apart."

Without a man and a woman, "it is impossible to have children," Barrios added. "Even same-sex couples have to go outside what they call a union, to get a child."

Protests both for and against a redefinition of marriage coincided with the start of oral arguments before the U.S. Supreme Court on March 26. The high court will rule this summer on two cases that could have drastic consequences for the way the nation understands marriage.

Defenders of marriage argue that the state has no right to redefine an institution that precedes it and is rooted in nature and biology. Men and women naturally come together to create children, and marriage is designed to reflect this unique reality, they argue.

Thousands of participants for the March for Marriage chanted "one man, one woman" in both English and Spanish as the March progressed along its route from the National Mall to the Supreme Court.

Organizers estimated well over 10,000 participants at the march, which was the first of its kind in the U.S.

Patricia Barley, of Durham, N.C., told CNA that she decided to march not only because she believes in the traditional definition of marriage, but also because "I think it's important that the Supreme Court and the government recognize the voices of the people."

Jim McCrery, a high school student from Washington, D.C., said that he was at the march because "though there is there separation of church and state, the country is still guided by morals."

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He added that he doesn't think two men or two women "can give what a man and a woman can give to their children."

Sister Bernadette Morse, a sophomore undergraduate student at Franciscan University said that although she was a religious sister, she was at the march to support marriage for all of society. She added that she hoped the protest would be a "visible sign" that Americans are united in defending the truth of marriage.

"I want my brothers and sisters to be able to receive the gift of marriage that God has given us, in order to make of themselves a whole gift and bring forth life as we were created for," Sr. Bernadette explained.

"It means everything to me because it's the way He called us to be fully alive through making a gift of ourselves," she continued.

Caitlin Seery, program director for the Love and Fidelity Network, came alongside more than 60 students from around the country, including some 40 from Franciscan University of Steubenville, Ohio.

 The Love and Fidelity Network is a web of more than 25 college organizations and hundreds of college students that support the traditional understanding of marriage and sexual ethics.

Seery explained that for college students, marriage is "very much on their minds," and they are "standing up" for their beliefs and the "child's right to a mother and father."

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Samantha Lei, who came from New York with her school-age daughter and her daughter's friend, explained that it is important for society to recognize that marriage is between a man and a woman.

"Kids grow up better with a daddy and a mom," she stressed, adding that she hoped "that the judges will listen to us."

"These are the fundamentals of America," she explained.