Duluth, Minnesota four Catholic schools with coverage up to grades 6 or 8, two Protestant schools, two Montessori schools, and six other charter and private schools. Due to its proximity to the Great Lakes, Duluth is the location for the Large Lakes Observatory. The Large Lakes Observatory operates the largest university-owned research vessel in the Great Lakes, the R/V Blue Heron. Built in 1985 for fishing on the Grand Banks, the Blue Heron was purchased by the University of Minnesota in 1997, sailed from Portland, Maine, up the St. Lawrence Seaway to Duluth, and converted into a limnological research vessel during the
Iron mining in the United States large size of the Lake Superior deposits, and the access to cheap Great Lakes water transportation, enabled iron mining on a massive scale, located far from the iron furnaces. The Lake Superior iron ores, however, are located far from coal deposits, and the greater tonnage of coal required in steelmaking favored the location of furnaces closer to the coal mines. Favorable locations for steelworks using Lake Superior ore included Great Lakes ports such as Chicago, Cleveland, and Gary, as well as cities close to coal and with good water transportation, such as Pittsburgh. Although Lake Superior provides cheap shipping most