Koppers Holdings Inc.
A maker of treated wood products, wood-preserving chemicals, and carbon compounds, Koppers is the largest North American supplier of railroad crossties, with brands like MicroPro-treated lumber. It traces its roots to German engineer Heinrich Koppers, who in 1912 brought his "chemical-recovery" coke oven to America, built to capture coal tar byproducts rather than release them into the air. That same coal tar is still distilled into creosote for the ties the company makes today.