The center of trade and commerce for the entire southwestern Oregon coastal region.

Coos Bay is the largest of the communities that comprise Oregon's Bay Area.

The area was inhabited by members of the Coquille Indian Tribe, the Confederated Tribes of Coos, Lower Umpqua and Siuslaw Indians, and the Siletz Indians for time immemorial, and they call the Coos Bay region their ancestral homeland. The name “Coos” is derived from the two distinct Tribal languages miluk and hanis, where “kuukus” and “gugwəs” are terms used for the Coos Bay region, signifying “South” in these languages. 

Since the 16th century, the area's dramatic beaches, promontories, blazing sunsets, endless stands of massive forests, golden dunes, and waters teeming with fish have awed explorers of the southern Oregon coast. Sir Francis Drake is believed to have sought shelter for his ship, the Golden Hinde, and its crew near Cape Arago in 1579. Trader and explorer Jedediah Smith came to the area for furs and the Hudson's Bay Company sent explorers to search for an inland passage.

Coos Bay, Oregon's largest bay, has represented a commercial passage to the sea from pioneer days to the present. In the mid 1800's, the waterways and forests that had supported the Native American settlements equally encouraged European settlement. Around the turn of the century coal, mining and shipment of coal were a major part of the economy, and the region prospered as a center for wood products, shipbuilding, shipping and products of the sea. Transportation systems radiated from the city to inland Oregon, the Pacific Ocean and other areas of Coos County. The mosquito fleet of small boats delivered people and products to places of pleasure, culture and transshipment to other parts of the world.

Marshfield was founded in 1853 by J. C. Tolman, who named it after his Massachusetts hometown. 

Empire City was founded in 1853 by members of the Coos Bay Company. Empire City post office was established in 1858 and ran until 1894, when it was renamed Empire.

The first Methodist church in the area was established in 1857.

The Cape Arago Lighthouse was built in 1866, west of Charleston, to direct traffic near the bay.

The Blanco Lodge, the 48th chartered Masonic Lodge in Oregon, was set up in 1870 by several of the town's founding fathers.

The Marshfield Post Office was established in 1871.

In 1872, the Coos Bay Wagon Road connected Coos Bay to Douglas County near present-day Roseburg.

The city of Marshfield was incorporated on October 24, 1874.

East Marshfield post office was established in 1891 and operated intermittently until 1908, when the name was changed to Eastside.

In 1916, a rail line was completed that linked the region to other interior settlements and towns, which increased commercial trade and tourism.

The Oregon Coast Highway, also known as US Route 101 or Highway 101, began construction in 1921 and was officially completed on October 3, 1936. US 101 is the main north-south thoroughfare through downtown, with Bayshore Ave northbound and Broadway Ave southbound.

In 1944, residents voted to change the City’s name to Coos Bay due to the community’s most prominent geographic feature. Marshfield officially changed to Coos Bay on February 15, 1945. The historic downtown is still known as the Marshfield District.

In 1964, the city of Empire merged with Coos Bay in December 1964 following a vote of the citizens and approval of Coos Bay City Council.

In 1983, the city of Eastside merged with Coos Bay in December of 1983, following the November vote and approval of Coos Bay City Council.