The economy of Ontario is the largest in Canada, representing almost 40% of the country's GDP. It is the second largest sub-national economy in North America, after California. Ontario's economy is highly diversified and is centered around the Great Lakes, which provide the province with abundant natural resources and access to international markets. The province is home to a large manufacturing sector, as well as a thriving services sector. Ontario is also a major center for research and development, and is home to some of the world's leading universities and research institutions.