A resident out for a walk found the baby at 2:15 p.m. in a wooded area roughly 10 feet from the shoulder of Southeast North Bend Way, according to Cindi West with the King County sheriff's office.
The location, which is near the Kimble Creek Bridge, is roughly a mile away from the Snoqualmie Casino.
West said the baby was "full term" with its umbilical cord still attached. She did not say if the baby was a boy or a girl.
A King County medical examiner came to the scene and removed the body while detectives collected evidence.
News of the tragic discovery sent shock waves through the community.
"I'm traumatized and devastated," said North Bend resident Russell Denison. "I'm a parent. I have two daughters and a son, and I can't imagine that."
The investigation is ongoing, and detectives are now trying to track down the child's mother and father.
"We're looking for somebody to help us identify who this baby belonged to," West said. "Somebody has got to know somebody who was pregnant recently that is suddenly not pregnant anymore, and there no baby is sight."
Detectives are asking anyone with information to call the King County Sheriff's Office at (206) 296-3311 or at 1-800-222-TIPS.