NEW YORK — After 25 years of marriage, there are still too many stories Gail Ostrow and her husband haven’t shared with each other.

She hasn’t heard the whole truth of what it was like in Vietnam. Or why, after the war, he retreated to 240 acres in Wisconsin to live without electricity and water. Or how he felt about not raising his son from a previous relationship.

“This is the man that I have lived with and loved and slept next to and been through some really great adventures and been through some really hard times together,” the 64-year-old college professor said. “But there hasn’t been a lot of talking.”

“There are things that I want to know about him that don’t come up in conversation.”

So on the day after Thanksgiving, Ostrow will sit down with her husband at their Bridgeport, Conn., home to interview him and record his words — joining thousands of people nationwide who are participating in the National Day of Listening.

Launched by oral-history organization StoryCorps and scheduled for a day when families are more often dashing to take advantage of Black Friday sales, the event seeks to give people a reason to sit down with friends and family and have intimate conversations that can be preserved as heirlooms.

“Stopping on Friday the 28th and taking an hour to interview a loved one is the least expensive but most meaningful gift we can give one another,” said StoryCorps founder Dave Isay, who said the idea was a response to the financial turmoil faced by so many Americans this year.

“This is the kind of project that can help us through difficult times by remembering what’s really important, and that all of our lives matter,” he said.

The national event is an outgrowth of Isay’s StoryCorps program, which since 2003 has helped people record nearly 25,000 interviews at booths in New York and with mobile operations traveling around the country. Participants receive a CD of their 40-minute interview, and all recordings are archived at the Library of Congress.

The memories and thoughts recorded Friday won’t be stored so permanently — Isay says StoryCorps simply doesn’t have the staff and resources to make that happen — but the real point, he says, is to allow families to preserve the recordings for themselves.

Such a do-it-yourself approach is more accessible than ever. People who may not even realize it often have digital recording equipment among their gadgets. Many computers can record sound directly, and even iPhones and some iPods can be used to record interviews. Participants can burn their own CDs of their conversations, or they can post them on online audio-sharing sites.

The experience creates more than a historical record to be shared with future generations. It can break down barriers and provide an opening for otherwise reserved participants to clearly voice their emotions.

When 29-year-old Seth Fleischauer recorded his interview with his grandfather, he heard the older man speak emotionally about their connection.

“I don’t think that, up until that point, he had expressed his intimacy for me in that sort of way,” Fleischauer said. “That was a really important bonding experience for both of us.”

Now the New York schoolteacher sees the National Day of Listening as an opportunity to mark a milestone with his fiancee, as he interviews her following the first Thanksgiving that they host together as their own family.

The chance to preserve memories and emotions has proven a powerful draw. When the National Day of Listening was announced Saturday on National Public Radio, which has broadcast edited StoryCorps interviews for years, the Web site promoting the event quickly crashed as tens of thousands of people attempted to view the site.

It’s not an unusual response, Isay says, noting that StoryCorps’ traveling recording booths, which typically offer 100 interview slots per town, are frequently deluged with requests.

“We will often see 5,000 or 6,000 requests for interviews within the first three minutes,” he said. “We’ll see people traveling hundreds of miles to come and record, and people showing up 10 hours early for interviews. And I think it’s because people think of this as an opportunity to leave a legacy.”

It is that wish to leave a mark that led Gail Ostrow’s husband — after repeated requests — to finally agree to be interviewed, she suspects. “He has a little more of a sense of his mortality” after an emergency surgery this year, “and maybe there are things he’d like to say,” she said.