Where SR 77 joins I-40 at exit 286, US 66 continued following I-40 Business and Navajo Boulevard north, then northeast, passing through the northeastern edge of Holbrook. At exit 289, US 66 took on the route of I-40, and split off again where exit 292 is today. US 66 followed an old roadbed on the north side of I-40 around the community of Sun Valley, then rejoined the Interstate at the edge of the Painted Desert. US 66 utilized a section of abandoned roadbed east of West Twin Wash, then crossed to a short section of roadbed and bridge on the south side of the Interstate at exit 300. US 66 rejoined I-40 and followed the eastbound lanes to the Painted Desert Indian Center, where the highway briefly split off onto the south frontage road. East of exit 303, US 66 rejoined I-40, where the frontage road curves to run parallel with the Interstate. US 66 diverged from I-40 where the south frontage road curves northeast and heads away from the Interstate.