In the rush to get through airport security checkpoints, it is not uncommon for distracted travelers to leave laptops, cellphones, jewelry and other valuable items in the plastic bins needed to scan their belongings.
As it happens, they also leave behind lots of accumulated cash.
For its fiscal year 2016, the Transportation Security Administration reported that passengers left behind more than $867, 812.39 in coins and currency in the plastic bowls and bins at various U.S. airport checkpoints. That's about $102,000 more than the amount left behind in 2015, and the more than $484,000 left behind in 2008.
Over the years, the amount of change left behind by travelers at airports has been steadily climbing—jumping from about $489,000 in 2011 to almost $675,000 in 2014, and hitting $766,000 in 2015.
"There is no real way for TSA to know why this happens," spokeswoman Lisa Farbstein told CNBC. "It makes sense to point to an increase in the number of travelers as one likely reason, but other than that, we have no theories."
Last year, passengers at New York's John F. Kennedy International Airport were the most forgetful (or generous, perhaps): Travelers there left behind $70,615 in unintentional 'tips' for TSA.
Also on the top ten list for fiscal year 2016: Los Angeles International Airport, where travelers left behind almost $45,000; and Dallas/Fort Worth International Airport, where more than $42,000 in cash and currency was abandoned.
What happens to all that money?
Back in 2005, Congress passed a law saying TSA gets to keep that unclaimed cash, and spend it on any sort of civil aviation security efforts it deems fit.
In at least two previous years' reports, TSA stated that the unclaimed money collected from airports would be used to support the expansion of the TSA Precheck program, which gives travelers expedited screening privileges. Precheck allows fliers to keep shoes and lights jacks on, and their laptops and quart-sized bag of liquids and gels inside their carry-ons.
When it filed its report on 2016's unclaimed cash haul, TSA said it had not yet determined how it would spend those funds.
At some airport checkpoints, passengers can also empty loose change from their pockets directly into donation bins for local charities before moving through the line.
During 2016, travelers passing through Denver International Airport donated $87,106.91 to Denver's Road Home, a non-profit that works with service providers for the region's homeless community. And last year passengers at Phoenix Sky Harbor International contributed more than $11,000 to help support the USO operations at the airport.
Travelers who want to be sure to walk away from airport security checkpoints with all their cash, coins and other small items, might consider following some of these tips offered by travel experts.
Use luggage or packs that have easily accessed exterior pockets, "and do all your stashing at home or office, or in the car before departing for the airport," said Chris McGinnis, editor of the TravelSkills.com blog.
"When you arrive at the airport door, you should have nothing in your hands or pockets but your ID and your phone and/or boarding pass," he added.
If you must empty cash and other small items into a bin, put them in a container that you place between your other pieces of carry-on luggage.
"That way there is no chance to miss it," said travel writer Ramsey Qubein of Daily Travel Tips." If you must remove your footwear, "put all your coins and other small items in a shoe," he added. "You won't forget them. Trust me."
—By Harriet Baskas, special to CNBC.com. Baskas is the author of seven books, including "Hidden Treasures: What Museums Can't or Won't Show You," and the Stuck at the Airport blog. Follow her on Twitter at @hbaskas. Follow Road Warrior at @CNBCtravel.