BNSF Railway train BNSF Z-SBDWSP9-21, carrying high-priority trailers headed for Willow Springs, Illinois, rounds the last curve on its ascent of its first series challenge to gravity since departing San Bernardino, just 25 miles (40 km) behind, as it reaches the apex of southern California's Cajon Pass on a somewhat snowy February 21, 2019. From here, there are still about 2200 miles (3540 km), more or less, to go and a lot more mountains to cross en route.