Washington Lottery spokesman Scott Kinney said the Washington ticket, purchased at a supermarket in Ephrata, was sold to a retired man who planned to bring his family to claim the winnings Thursday.
The holder of the other winning ticket, purchased just 125 miles away in Post Falls, Idaho, remained unknown.
A day after the drawing, all eyes were on a region where most of the nation's frozen french fries are produced, and on the similarity between the winning digits and the ones used by a character on the television show "Lost."
The winners had to match five regular numbers plus the "Mega ball."
The winning numbers were 4, 8, 15, 25 and 47, with the Mega ball number of 42. Four of the six winning numbers matched numbers that were prominently featured throughout the popular series - 4, 8, 15, 16, 23 and 42.
Video producer Ryan Jones of New York said he and a co-worker pooled their money to buy 10 tickets together, but he returned to the grocery store to buy an 11th entry just to play the "Lost" numbers.
Mega Millions said 25,587 tickets matched three of the winning numbers, plus the bonus number - so anyone who played the "Lost" numbers won $150 per ticket.
"When the numbers popped up, I did have a moment where I thought: 'You know, I could take this money and run, just get far away from Sarah and not share it with her,'" he said.
Jones added he decided to share the prize.
Character Hugo "Hurley" Reyes became a multimillionaire on "Lost" when he won using numbers repeated by a former Navy seaman who became a patient in a mental institution. Hurley was also a patient.
But his win came with a series of spectacular misfortunes - his grandfather died after a heart attack at Hurley's press conference and the house he bought for his mom caught fire.
Hurley even believed he caused a plane crash that left him and fellow passengers stranded on an island as the saga began. He blamed it on the numbers.
Jones said he's been ribbed many times since Tuesday's drawing that he may now be cursed.
"You know what, I think that I'm willing to take the curse in exchange for the $150," he said. "Let it come, I say."
At the Safeway in Ephrata, there were no curses. Only customers, coming in one by one, and placing their tickets into a machine to see if they had won something, even a few dollars. More than 5.5 million people won prizes, ranging from $10,000 to $2.
Most at the supermarket, however, turned away disappointed, tossing their tickets into a nearby trash can.
"We know as much as anyone else does," said Nathan Arlantico, 21, the video department manager. He said the store was busy with lines of potential millionaires all day Tuesday.
Because of feverish sales right up to the evening drawing, the winners will share a $380 million jackpot, an increase over the previous $355 million estimate, Kinney said.
In March 2007, two winners, in Georgia and New Jersey, shared the richest prize - a $390 million Mega Millions jackpot.
In Idaho, the lucky winner also has the option of taking a nearly $81 million lump sum payment after state and federal taxes are withheld, said Jeff Anderson, executive director of the Idaho Lottery.
No state taxes would apply in Washington, where the lump sum payment would be $90 million after the 25 percent federal tax.
The lives of the big winners will most certainly change, but for others, the lottery will be a fun memory.
"Lost" fan Hunter Hart of Los Angeles said he bought a ticket worth $150 because he found an extra $3 in his pocket while at a gas station. At first, he said, he wanted to keep it as a souvenir to say he played Hurley's numbers.
When asked what he planned to do with his winnings, the 26-year-old Internet entrepreneur said: "Well, I'm actually at the bar right now spending it.
"It's been a rough month, dude," he said.
Associated Press writers Nicholas K. Geranios in Ephrata, Wash., Jessie L. Bonner in Boise, Idaho, Phuong Le in Seattle and Oskar Garcia in Las Vegas contributed to this report.