By Wednesday, the unremarkable white house at 2207 Seymour Ave. in Cleveland was a tourist destination. Before that, it might as well have been invisible.

Three young women were held captive for a decade in the house, an eight-minute drive from where they were snatched. They broke free this week to find a world where technology has made it close to impossible to hide much of anything for very long.

“When these children were taken, Amber Alert was just coming on line,” said Robert G. Lowery Jr. of the nonprofit National Center for Missing and Exploited Children. “It has grown much more effective. We can reach the public almost instantaneously.”

Six years before the first of the Cleveland captives — Michelle Knight — was grabbed off Lorain Avenue, the body of 9-year-old Amber Hagerman turned up in a Texas creek. Today, the phrase “Amber Alert” has a secure place in the American lexicon, and it would be harder, Lowery said, to get away with snatching two teenage girls and a young woman from the streets of a U.S. city.

Police receive about 800,000 missing-children reports a year. But most of the children are found within a few hours, and 98.5 percent return to their families, Lowery said. About 200,000 of them disappear with a family member — often a noncustodial parent — and 15,000 are reported missing after being taken by a babysitter, a neighbor or a family friend.

The number snatched by a stranger — a pedophile, someone after a ransom or someone operating under circumstances like those in Cleveland? About 100 to 115 children a year, Lowery said.

With Amber Alerts, fewer missing children turn up dead than in the past. If a kidnapper is going to turn killer Lowery said it usually happens within the first two or three hours.

“When an Amber Alert goes out, there is so much public pressure on the abductor that they often release the child before they can get hurt,” Lowery said. “The vast majority of children now escape death because of Amber Alert.”

A vast apparatus is triggered when an alert is sounded, and the ensuing search often receives wall-to-wall coverage on the cable news networks. A child who is missing for an afternoon in rural Nebraska makes the CNN broadcast watched in suburban Beijing.

The story and pictures of the missing child are transmitted quickly. Video recordings from the surveillance cameras that keep watch over much of public America are scrutinized. Overhead signs on major highways flash information. Tip lines are activated. Twitter and Facebook light up with alerts. Known sex offenders are accounted for. Police study images from traffic cameras.

Just coming on line is the ability to send Amber Alert information to every smartphone within range of cellphone towers near where a child disappeared. Another technological advance improves the odds of finding a victim who has been held captive for years: the ability to create portraits that show how a missing person might age.

The Cleveland scenario is certainly unusual in the annals of kidnapping, a word that entered the language when Charles Lindbergh’s baby boy was snatched from his second-floor nursery in 1932.

Three women, Amanda Berry, Michelle Knight and Gina DeJesus, who went missing separately about a decade ago have been found alive in Cleveland, Ohio.

The three missing persons — two of them teenagers — were allegedly abducted and held captive by three men for reasons other than ransom. They were held captive for about 10 years in the middle of the city where they lived and where their disappearance was heavily publicized, though without the technological megaphone of Amber Alert.

In the end — unlike many cases in which strangers snatch children — they turned up alive.

“This is a situation we’ve not seen before,” Lowery said. “There’s generally a lone person involved in these situations. But in cases where people have been recovered [alive], it’s usually taken more than one person to restrain them.”

Lowery said Cleveland police “did a very extensive investigation until very recently.”

But once the three women disappeared behind the chain-link fence — in a nation where backpacks explode, where gunmen invade movie theaters and grade-school classrooms, and where Americans are urged to remain vigilant against the unusual — nobody really noticed anything amiss at 2207 Seymour Ave.