Duluth is a city of about 87,000 people in northern Minnesota. It is one of the most scenic cities in the Midwest. Duluth has always been a shipping town: first for furs, later for iron ore, timber, and grain. As a shipping and milling town, Duluth once had the highest number of millionaires per capita in the United States. This is still reflected in the large number of mansions in the east end of town. Ocean-going vessels come up the St. Lawrence Seaway into the Great Lakes to Duluth Harbor. Since these "salties" go through the locks, they are smaller than the native "lakers" that stay within the Great Lakes. Ships under many flags, including Nigeria, Greece, and Denmark frequently dock in Duluth to pick up grain and coal for overseas markets. Iron-ore and taconite still go to Indiana, Ohio, and Pennsylvania for processing into steel. Built largely on a 700-foot hill overlooking Lake Superior, Duluth also has a thriving tourism industry, with antique shops, excellent restaurants, cozy inns, and scenic views of the lake. There is a ski resort inside city limits. Canal Park and Superior Street have the highest concentrations of tourist destinations in the city. The famous Aerial Lift Bridge is on Lake Avenue, next to Canal Park. Particularly proud residents liken the city to San Francisco, which also has bridges, hills, a bay, and a thriving tourist business. The renowned Grandma's Marathon is held annually, named after Grandma's Saloon (restaurant) in Canal Park. The University of Minnesota-Duluth and St. Scholastica College are the two largest colleges in the city with over 12,000 students together. Duluth is the western endpoint of the scenic North Shore Drive, which follows the rugged north coast of Lake Superior nearly 700 miles to Sault Ste Marie (Ontario). Across the bay is Superior, Wisconsin. Due to the close proximity of Lake Superior, a deep lake and the largest freshwater lake in the world by surface area, Duluth can be cool or cold anytime of year. The official temperatures are reported from the airport, over the hill, and can be ten or more degrees (Fahrenheit) above the downtown temperatures. Sixties (18'C +/-) for a high in August are not uncommon, but it can reach the 80's (about 28'C) just as easily. Bitter windchills can occur in the winter, although air temperatures generally do not go below -20'F (-29'C). Despite this, some people bike to work year-round.