The five interconnected Laurentian Great Lakes define a vast, complex, socio-ecological system that is characterized by superlatives. The combined LGL watershed area is home to nearly 30 million people, or ten percent of the U.S. population and 32 percent of the Canadian population. Nearly 28 million of the region’s human inhabitants live in coastal communities greater than 100,000 each. The U.S. shoreline is nearly 16,000 km - a distance, longer than the U.S. continental coasts of the Atlantic and Pacific oceans combined.

When combined with the Canadian Province of Ontario, the region supports the 3rd largest economy in the world (if counted as a country), and is thus an economic engine of global significance producing in excess of $4.7 trillion in economic output in 2011 alone. Major industries in the region include agriculture ($15 billion annually), shipping ($35 billion annually), recreational fisheries ($7 billion annually), recreation ($4 billion annually), and tourism ($16 billion annually).

Hydrologically, all five lakes rank among the planet’s 10 largest lakes by area, and among the top 15 largest by volume, covering a surface area of 244,000 km2, and holding 22,000 km3 of water. They are large enough to affect regional weather patterns and climate. In addition, the LGL region covers distinctive climatic and soil types , supports globally significant aquatic biodiversity, and is critical in regards to the ecosystem services it provides.