Several people have gone missing in national parks across the country in the past week

• Several people have gone missing in national parks across the country this week.
• It's unclear how many people go missing in national parks each year.
• There are 29 cold cases of people missing in national parks dating as far back as the 1950s.

Multiple people have gone missing in national parks across the country over the past week as authorities search for Gabby Petito, a 22-year-old woman who was last heard from while visiting Grand Teton National Park in Wyoming.

Petito was reported missing by her mother on September 11 after she hadn't heard from her daughter since receiving a text on August 30.

Petito was on a cross-country road trip with her boyfriend Brian Laundrie before she disappeared. Laundrie returned to his family home in Florida on September 1 without Petito but has since also been reported missing.

Others have gone missing in Grand Teton in the past few weeks. The Jackson Hole News and Guide reported that Robert "Bob" Lowery, 46, of Texas has been missing since August 20.

Even more have also gone missing in national parks across the country since September 12. Authorities in Grand Canyon National Park used air and ground search efforts to locate Clifton "Cliff" Beck, 66, of Maryland after he was reported missing last Sunday. Beck, who was hiking alone, was found alive as of Friday, authorities said.

In Washington, officials are searching for Jerren Fisher, 26, who was supposed to return from a solo hike in Olympic National Park on September 12.

On Thursday, two kayakers were reported missing at Pictured Rocks National Lakeshore in Michigan on September 16. MLive reported that as of Friday, search and rescue efforts found that one had died and on Saturday, the Associated Press reported the second body was found. Officials did not release any names.

Last weekend, officials said Joel Thomazin, 31, of California was missing in Yosemite National Park after he never came home from a solo hiking trip that was supposed to end on September 9, KNTV reported.

There is no database of how many people go missing in national parks every year but the National Parks Service has at least 29 cold cases of people who have gone missing and have yet to be found, with the oldest case dating back to 1958.

The National Missing and Unidentified Persons System reported that more than 600,000 people go missing in the US every year, but the majority are quickly found, "alive and well," but there are tens of thousands of cold cases, where someone is missing for over a year.

As of Saturday, there were 20,685 open missing person cases across the US.