The northeastern portion of Ohio is commonly referred to as "Polymer Valley" due to the large number of rubber and plastic companies centered there since the late 1800s. Summit, Mahoning, Stark, Portage, Trumbull, and Columbiana Counties principally constitute Polymer Valley. In the 1980s and 1990s an influx of new polymer companies came to the region to take advantage of the area's mineral and transportation resources, as well as due to the skilled workforce. Scientists at the University of Akron and Case Western Reserve University are world renowned for their research into polymers and the quality of their graduates specializing in polymer engineering. Local high schools even offer specialized classes in polymer manufacturing. Forty-five percent of Ohio's polymer industries are located in northeastern Ohio. Due to the educational, mineral, and transportation resources of the area, this section of Ohio has earned its reputation as the center of polymer manufacturing in the United States.