Great Lakes Mesoscale convective complexs or MCCs can cause damage to wide swaths of forest and shatter glass in city buildings. These storms mainly occur during the night, and the systems sometimes have small embedded tornadoes, but more often straight-line winds accompanied by intense lightning. Historically, the Great Lakes, in addition to their lake ecology, were surrounded by various forest ecoregions (except in a relatively small area of southeast Lake Michigan where savanna or prairie occasionally intruded). Logging, urbanization, and agriculture uses have changed that relationship. In the early 21st century, Lake Superior's shores are 91% forested, Lake Huron 68%, Lake Ontario
The Great Lakes Group was the first president. The company began full operation on the Great Lakes (except Lake Ontario and the St. Lawrence River) in 1900, starting its first navigating season with over 150 tugboats. The Company grew rapidly, so much so that in 1913 it was charged with operating a monopoly. Frequent labor unrest during World War II resulted in the U.S. government assuming control of the Company in 1945-46. During the 1950s and 1960s the company installed innovative communication equipment. Business began to decline in the 1960s when the decline of the steel industry and the introduction of new types of