The two containers of liquid in the female passenger's carry-on bag tested positive for an explosive, prompting the evacuation at the Huntington Tri-state Airport, the US Transportation Security Administration said in a statement.
West Virginia state police then checked the carry-on luggage with bomb-sniffing dogs and also detected a suspicious substance.
A hundred people were evacuated from the terminal to another airport building, Tri-state Airport Director Larry Salyers told CNN television.
The Federal Bureau of Investigation was questioning the woman, who was from Jackson, Michigan, but had lived in the Huntington, area of West Virginia, the airport director said.
"The lady is in custody," Mr Salyers said, adding that the woman was born in 1978.
The incident comes a week after British police disrupted an alleged plot to bomb US-bound airliners leaving Britain. The suspected bombers planned to use liquid explosives, authorities said.
The case prompted the US government to ban passengers from carrying liquids and gels on commercial aircraft.
Flights out of the West Virginia airport resumed on Thursday afternoon, the TSA said in a statement.
Sydney scare
Meanwhile, a passenger onboard a plane at the centre of a bomb scare in Australia has said he feared the aircraft would explode.
Mark Singleton was one of 102 passengers evacuated from the Pacific Blue 737 from Fiji to Sydney on Thursday night amid a bomb hoax.
After being kept in the dark by airline staff about what was happening, Mr Singleton said he concluded a bomb threat was likely when the plane was surrounded by emergency crews.
He has told how he thought the plane would explode while passengers were cooped up in a bus, where they waited for 45 minutes on the Sydney Airport tarmac after being evacuated from the plane.
"That's probably the only time when I felt a little bit scared,"
Mr Singleton told the Nine Network.
“We were sitting on a bus facing this plane maybe a 100 metres back and people were using their mobile phones against orders. No one was telling them not to and I thought if the bomb's going to be detonated now will be the time."
The drama unfolded after an anonymous caller warned there was a suspicious package onboard the plane, which landed at Sydney Airport from Fiji about 5.45pm (AEST).
NSW Bomb Squad officers scoured the aircraft but declared the bomb scare a hoax about 7.45pm.
Mr Singleton said the response to the scare was chaotic and could have been better organised.
He said passengers were given "erroneous excuses" about why the plane was delayed on the tarmac when it was clearly surrounded by emergency crews.
Mr Singleton said passengers, who had to wait on the plane for about an hour before being herded on to the bus, were only made aware of the bomb scare later by friends and the media.
UK airports ‘back to normal’
Amid the latest incidents in the US and Australia, flights were virtually back to normal at major British airports, a week after police thwarted an alleged plot to blow up US-bound planes.
British Airways, which has scratched more than 1,900 flights over the past week, said it was cancelling only 19 short-haul flights from Heathrow airport on Thursday.
"We should be back to a full service by Friday," a BA spokesman said.
Police have kept 23 young British Muslims in custody after a judge agreed that more time was needed to question them.
Under British law, terrorism suspects can be detained by police without charge for a maximum of 28 days, subject to court approval.
The alleged apparently involved suicide bombers smuggling liquid explosive disguised as drinks onto US airliners, then detonating them with electronic devices mid-air.
Three arrests in Pakistan, including one involving a British
man, Rashid Rauf, whose brother is among the 23 being held by
London police, has prompted speculation that Osama bin
Laden's al-Qaeda network was involved.