If congestion doesn't improve over the next decade, the researchers said, that stretch of I-95 will cost local motorists $2.3 billion in wasted time, lost fuel and additional carbon emissions.
Nationwide, continued traffic congestion could cost drivers $2.2 trillion over the next decade, the study found.
Bob Pishue, an INRIX senior economist, said researchers put a dollar figure on backups studied in more than 100,000 "hot spot" road segments in March and April to help public officials target improvements. Being able to prioritize transportation spending, he said, is particularly important since the Trump administration has proposed $1 trillion in infrastructure investments.
Quantifying the costs of traffic congestion, Pishue said, will help government officials weigh the costs and benefits of improving roads or expanding transit in different areas.
Researchers didn't say how traffic should be alleviated.
"The investments should go into areas that would get the most bang for the buck," Pishue said. "If those funds go to where drivers are feeling the most pain, it will go a long way in gaining public support" for additional infrastructure spending.
Overall, the Washington region ranked third in the United States, behind Los Angeles and New York City, for the 10-year costs of traffic congestion. Los Angeles motorists face a potential $91 billion, while New York City drivers could lose $64 billion to backups.
Atlanta came in fourth with $29 billion in potential costs over the next decade, and Dallas came in fifth with $28 billion.
INRIX, which collects data from sensors on vehicles and motorists' cellphones, usually ranks cities' traffic misery by focusing on motorists, such as how much time they spend in backups.
This time, Pishue said, researchers examined traffic in different road segments.
The Washington area had two other traffic "hot spots" among the 25 worst, the study found. Northbound I-95 from an area south of Fredericksburg to Exit 143 (Garrisonville Road), also in Northern Virginia, came in seventh with 936 traffic jams over the two-month study.
In Maryland, the eastern part of the Capital Beltway between Kenilworth Avenue (Route 201) and just east of the Woodrow Wilson Bridge in Prince George's County ranked ninth worst with nearly 700 backups.
John B. Townsend II, a spokesman for AAA Mid-Atlantic, said he wasn't surprised to hear I-95 in Northern Virginia had earned such a dubious distinction.
The highway's 29 miles of express toll lanes, which opened in 2014, have given motorists willing to pay a faster, more reliable option and freed up more space in the regular lanes, he said.
They've also caused more backups where the toll lanes end and vehicles have to merge into the regular travel lanes.
"In one way they're a godsend because they've lived up to their promise of creating faster commute times on I-95," Townsend said. "But we're seeing these slowdowns in the regular lanes. You just get these backups up and down the line . . . At the end of the day, you still save time."
Kelly Hannon, a spokeswoman for the Virginia Department of Transportation, said the state will spend $800 million over the next five years to improve I-95 in the Fredericksburg area.
She said traffic is particularly congested there because local motorists who use I-95 as a Main Street for errands mix with regional commuters, tractor-trailers and long-distance travelers.
"Any incident can cause delays very quickly," Hannon said. "It's just a very fragile system whenever anything unexpected happens."
The state has started extending the express toll lanes two miles to the south and plans to build another 10 miles of them south to Route 17 (Exit 133), Hannon said.
It's also planning to build three new southbound lanes in the median to separate local and through traffic between Exit 133 and Exit 3 (Route 3).
Stewart Schwartz of the Coalition For Smarter Growth said adding more lanes will only attract more traffic. He said I-95's continued congestion, even in areas with express toll lanes, shows additional lanes only makes it easier for more people to drive.
He noted Maryland Gov. Larry Hogan (R) recently proposed adding express toll lanes on the Beltway, Interstate 270 and the Baltimore-Washington Parkway.
Northern Virginia's roads won't see relief, Schwartz said, until the region's growth plans insist on more affordable housing closer to jobs and transit options.
"Without that," he said, "you're going to keep the pressure on that highway."