Northernmost of the lower 48 states, Minnesota holds a pivotal position. The Great Lakes waterway system gives access to the Atlantic Ocean; the Mississippi River, which rises here, provides a link to the Gulf of Mexico. Duluth is one of the world's largest inland ports, transshipping low-grade iron ore, much of it from the nearby Mesabi Range, source of more than three-quarters of U.S. output. Agriculture dominates the state's south; agribusiness clusters in metropolitan Minneapolis-St. Paul, also a magnet for high-tech growth and the cultural center of the upper Midwest. With 15,000 lakes, Minnesota attracts many summer visitors.