Discover the geography, history, and purpose of Lake Erie, which is the smallest of the five Great Lakes, and creates the northern shores of Ohio. Formed by glacier activity during and following the Ice Age, Lake Erie joins the rest of the Great Lakes to provide 90% of all of the water in the United States. Lake Erie was named after the Native Americans--the Erie people--who settled along its shores. In more recent years, Lake Erie has suffered from population growth, industrialization, and the resulting pollution. In the 1960s, it was considered dead by environmental activists. Today, its water quality is improvoing as it benefits from the Clean Air Act passed by the United States government. Finally, it is an important transportation route connecting to the Atlantic Ocean.