In June 1966 construction began on a railroad spur to provide reliable rail service from Great Northern Railway’s main track to Boeing's Everett plant for the construction of the 747. However, all paths to the site were very steep and spanned rough terrain. The challenge involved laying two miles of track up a gulch which rose 540 feet from the Great Northern tracks at Mukilteo, Washington, to the plant site. The December 1966 issue of Boeing Magazine reported that the roadbed’s constant grade of 5.6 percent made it the second steepest standard gauge in the United States, bested only by the Pennsylvania Railroad’s 6.3 percent spur near Madison, Indiana. Nearly 1 ½ million cubic yards of earth were moved to build the line. Eight miles of drain line were used to protect the roadbed from water runoff down the gulch. Now operated by the BNSF Railway Company, the rail spur continues to be a vital part of the Everett plant’s operation.