Brenda Hillman's poem "Air for Mercury" was published in her 2001 collection Cascadia, which most critics acknowledge is Hillman's most ambitious work, if not her most accessible work. The volume was inspired by Hillman's love for her adopted state of California. Cascadia refers to the prehistoric landmass that predates California and America's West Coast—a landmass that was submerged under the ocean more than 100 million years ago. In Cascadia, Hillman uses this ancient geological occurrence as a springboard to map the various geological and cultural characteristics of modern-day California.