After the attacks, barriers and thigh-high cement bollards sprouted up seemingly overnight in Washington, D.C. But new threats show the need for adaptability.

At least 67 undocumented immigrants, mainly from Mexico and South America, who worked at the World Trade Center on Sept. 11, are still considered missing.

President Biden called on Americans to embrace unity as they reflect on the day that two decades ago reshaped the nation. "Unity is what makes us who we are: America at its best," he said.

Students today have no memory of the attacks of Sept. 11, 2001, so this year's anniversary poses unique challenges for educators and caregivers trying to explain what happened and why.

While America was under attack on 9/11, Cincinnati voters were holding their first mayoral primary. "It was the oddest day of my career in politics," said then-mayor Charlie Luken.

An 8th grader at the time of terror attacks and her father remember how they felt as members of a minority group living in the U.S.

In the weeks leading up to the 20th anniversary of 9/11, NPR set up a phone booth in New York City and invited people to leave voicemails for someone they lost that day. Here's what they had to say.

John Murphy and Tim Lombardi arrived in New York City on September 12

Twenty years is a long time, a generation. But the Sept. 11, 2001, terrorist attack on the World Trade Center in New York City can still feel very fresh for those who watched it unfold, in person or on television.

After the terrorist attacks on Sept. 11, 2001, WKSU's reporters and producers spoke with Northeast Ohioans about their reaction to the tragedy.

Many children of 9/11 victims were too young to remember their parents who died. They've grown up living with the tension between having a personal connection to the day but few, if any memories.