"The flooding levels we're looking at are potentially historic in nature," Gov. Bob Ferguson said Thursday afternoon, urging people to listen to official advice and follow evacuation orders.

The urgency went up a notch in Mount Vernon Thursday night, amidst concerns about whether the levees and dikes will be able to hold a record crest.

Unprecedented flooding is driving tens of thousands of people from their homes. Local authorities are sharing resources, and the state is asking for federal aid.

Authorities have told everyone within the Skagit River's 100-year floodplain to evacuate ahead of rapidly rising floodwaters. Communities including Burlington, La Conner, Lyman and Hamilton, as well as parts of Mount Vernon and Sedro-Woolley,

A century-old Skagit River dike is holding as 75,000 residents remain under evacuation orders. Officials warn flood risks will continue into Saturday morning.

Historical newspaper accounts archived by Skagit County trace flooding in the region back to the late 19th century, long before modern flood control measures were in place.