Where I-80 runs through Placer County, over 1,400 firefighters battling a series of damaging grass fires in made progress overnight amid cool, relatively windless skies, saying on Friday that the blaze was nearly one-third contained.
No cause has been determined for the Applegate Fire, which had burned 420 acres by Friday morning.
One thousand homes in the communities of Applegate and Weimar were still threatened, with six having burned down, and hundreds of people remained under orders to evacuate.
All lanes on eastbound I-80, which was temporarily closed after the fire broke out Wednesday afternoon, were reopened Thursday night.
Fire officials said containment lines near the threatened communities north of Auburn had been strengthened, but because of downed power lines and trees at risk of falling, evacuation directives remained in effect.