Historically, the Pacific Northwest had been inhabited by Native Americans. Starting from about 15,000 years ago, Native Americans settled along the coastline and along the major rivers. From the 1500s to the 1700s, Europeans explored the region, beginning with the discovery of Oregon and Washington. In the early 1800s, the famous Lewis and Clark expedition arrived in Washington State. From the 19th century to present day, the region began to become settled. Today, the largest cities in the Northwest include Vancouver, Seattle and Portland.