Correction 8/22/13: A previous version of this story contained errors. It overstated the contributions received by the Yes on 522 campaign and the share of donations received from Washington state. The Yes campaign has amassed $3.5 (not 3.9) million, with 79 (not 71) percent of the funds coming from out of state. The nonprofit MapLight, based in Berkeley, Calif., informed us on Aug. 21 that it had double-counted some contributions, which led to the errors.

Backers of a Washington state ballot initiative to require labels on genetically modified foods have raised nearly four times more cash than their opponents.

Both sides’ contributions have come mostly from outside Washington state.

Supporters of Initiative 522 have raised $3.5 million in their quest to have genetically engineered foods labeled in Washington. Opponents have raised $952,000, according to the state’s campaign-finance database.

The biggest spender in the labeling debate is already known for labels of a different kind.