Lewis and Clark arrived in the early 1800's witnessing a significant Indian population along the banks of the Yakima and Columbia Rivers. Nearly a century later, Kennewick had 30 businesses, and the population was nearly 350 residents. In 1904, the citizens of the town voted in favor of incorporation. Kennewick was known for its spring crops, because of the mild winters in the region. There were also plentiful apple and cherry orchards, as there are today. Not a decade later, Concord grapes were a common crop and Kennewick staged an annual Grape Festival which continues to this date.

As of 1950, Kennewick's population grew to over 10,000. In the next two decades, Kennewick and the other Tri-Cities benefited from the completion of the Columbia Basin Irrigation Project, which provided affordable hydropower. The construction of three Washington Public Power Supply System (WWPPSS) nuclear plants at Hanford in the 1970s provided an economic boost to all of the Tri-Cities, making the area one of the fastest growing in the nation.

More recently, Kennewick has become famous for Kennewick Man discovered at Columbia Park during the annual Water Follies hydroplane races. He is the oldest known inhabitant of the area. His skeleton has been dated at 9,200 years old, making it the oldest nearly complete skeleton ever found in North America. Today, Kennewick is the largest of the Tri-Cities with a population of roughly 80,000 and is poised for future prosperity and growth.