Coos Bay is the homeland of two bands of Native people, Miluk and Hanis.

[5] Early maps and documents spelled it Kowes, Cowes, Coose, Koos, among others.

[4] Although exploration and trapping in the area occurred as early as 1828, the first European-American settlement was established at Empire City in 1853 by members of the Coos Bay Company; this is now part of the city of Coos Bay.

Since the turn of the century it has become a strongly Republican county in Presidential elections as a result of various factors including de-unionization in the timber industry and opposition to environmental policies often championed by Democrats.

The last Democrat to win a majority in Coos County was Michael Dukakis in 1988, although Bill Clinton won pluralities in both his elections.

Barack Obama, in both of his presidential campaigns, was the most recent Democrat to even break 40 percent of the vote in Coos County.

Deposits of gold initially attracted people to the county in the nineteenth century.

A project to build a 60-mile (97 km) natural gas pipeline between the cities of Roseburg and Coos Bay, which would attract new industry to the Coos Bay area, was begun in 1999 when voters approved a local bond measure to raise as much as $27 million, with the state of Oregon providing $24 million.

Currently, forest products, tourism, fishing and agriculture dominate the Coos County economy.

Boating, dairy farming, myrtlewood manufacturing, shipbuilding and repair and agriculture specialty products, including cranberries, also play an important role.

Untapped rich deposits of iron ore and lead await development.

The Jordan Cove Energy Project is a project that was met with resistance since 2010 by farm owners and other land owners, tribal natives, and some commercial entities who did not want their land being used or taken without their permission, with eminent domain.

A current project underway in Coos County, undertaken by Oregon Resources Corporation (ORC), uses modern strip-mining techniques to extract chromite, zircon, and garnet from local sands.

[17] The tailings after processing will be returned and re-contoured to replicate pre-mining conditions, and the affected area will be reforested.

[18] The Oregon League of Women Voters cited similar numbers from ORC, wholly owned by Industrial Mineral Corporation of Australia; the operation was projected to create 70 to 80 jobs with a salary of $46,000 per year.

The tallest documented living specimen of a Douglas-fir tree in the world is found 35 miles (56 km) southeast of Coos Bay in the Sitkum area[20] and is slightly more than 100 metres (330 ft) tall.