| Year | Event |
| Time Immemorial | Salish-speaking people live throughout the Chehalis watershed. The rivers provide a major source of food. The rivers also served as a highway for traveling through the country in shallow canoes. Two principal tribes existed - the Lower Chehalis and the Upper Chehalis. The name "Chehalis" (meaning "sand") originally referred to a village near the present-day Westport and later came to be applied to the river and the people living upriver. |
| 1000 B.C. | Athabaskans arrive in the Boistfort Valley |
| 1792 | Captain Robert Gray names Grays Harbor (May 7) |
| 1792 | Captain Gray and Indians clash on harbor (May 8) |
| 1804 | Lewis & Clark expedition |
| 1824 | John Work, employee of the Hudson's Bay Company, travels up the Chehalis River and describes the Chehalis River people - mentions several villages along the Chehalis River and additional settlements up the Black River. Unlike their downriver neighbors, the Upper Chehalis have horses. |
| 1841 | Captain Wilkes estimates the population of the Upper Chehalis to be 700 |
| 1845 | Joseph Borst settles on the Chehalis River |
| 1850's | Early settlers begin grazing cattle on the Hoquiam tideflats; cattle are shipped by scow up the Chehalis River, then herded to Olympia |
| 1851 | Settlers begin farming the Boistfort Valley |
| 1851 | Anson Dart, Superintendent of Indian Affairs, tries to negotiate a treaty with the Chehalis Tribe - treaty would move coastal people to the east of the Cascades; Dart obtains "signatures" but none of the promised payments arrive |
| 1852 | George Washington, son of a slave, founds Centralia |
| 1853 | Washington Territory created |
| 1854 | George Gibbs makes a census of Western Washington tribes - estimates the Upper Chehalis numbers 216 |
| 1854 | Chehalis County created (now Grays Harbor County) |
| 1855 | Fort Henness built near Grand Mound |
| 1855-56 | Indian uprising spreads across the mountains - Chehalis Indians do not take an active part |
| 1855 | Governor Isaac Stevens negotiate treaties with coastal tribes in Cosmopolis - Chehalis Tribes refuse to accept treaty terms (a reservation somewhere between Cape Flattery and Grays Harbor) |
| 1858 | Government attempts to enforce laws against cutting timber on public lands |
| 1859 | Steamboats travel to Montesano |
| 1860 | Construction of Fort Chehalis at Westport |
| 1861 | First commercial oyster beds in Grays Harbor |
| 1864 | Chehalis Reservation (4,200 acres) created by executive order |
| 1879 | Industrial Boarding School established on Chehalis Reservation |
| 1882 | Captain Asa Simpson buys 300 acres of timber at the mouth of the Hoquiam River and builds the North Western Mill |
| 1882 | Pope & Talbot buys lumber mill - Cosmopolis becomes a company town (Grays Harbor Commercial Co.) |
| 1883 | First newspaper in Grays Harbor County |
| 1884 | A.J. West lays foundation timbers for Aberdeen's first sawmill |
| 1884 | Aksel Seaborg builds salmon cannery in Aberdeen - Finnish settlement spreads to Grays Harbor |
| 1884 | Splash dams begin operation in Grays Harbor |
| 1885 | First train arrives in Montesano |
| 1886 | Montesano becomes seat of Chehalis County |
| 1890 | Aberdeen incorporated (May 12) |
| 1890 | Hoquiam incorporated (May 24) |
| 1891 | Cosmopolis incorporated |
| 1892 | Northern Pacific Railroad builds a line from Chehalis to Grays Harbor; company selects Ocosta as the railroad's terminus and plats over 300 lots |
| 1900-30 | Appalachian highlanders flow into Lewis County and the Chehalis basin |
| 1903 | Aberdeen fire destroys 22 city blocks |
| 1906 | Chehalis Tribe petitions federal government for payment for appropriated lands |
| 1908 | Aberdeen Daily World |
| 1910 | 34 lumber and shingle mills line Aberdeen harbor and Chehalis River estuary - population reaches 17,000 (1995 population - 16,700) |
| 1911 | Whaling station established at Bay City by American Pacific Whaling Company |
| 1914 | Finns settle in the Grayland area and pioneer area's cranberry industry |
| 1911-17 | Grays Harbor booms with mills, salmon and clam canneries, and shipbuilding yards; introduction of steam ships and global market changes economics of lumber industry - wages begin to fluctuate resulting in labor unrest |
| 1914 | Swedes, Finns, Italians, Greeks, Germans, English, Irish, Scotch, French, Swiss, Chinese, and Japanese take part in Fourth of July parade in Aberdeen clad in "old-fashioned costumes of the country" |
| 1914 | Westport incorporated |
| 1915 | Chehalis County changed to Grays Harbor County |
| 1916 | Grays Harbor jetties completed |
| 1919 | Industrial Workers of the World clash with Legionnaires in Centralia |
| 1929 | Last lumber mill in Doty closes |
| 1929 | Grays Harbor Commercial Company in Cosmopolis closes (Eventually bought by Weyerhaeuser Company) |
| 1930's | Depression idles 9 major Grays Harbor mills; owners of operating mills hire Filipino and Hindu workers to replace strikers |
| 1930's | 60,000 acres of Capitol Forest purchased by State of Washington for fifty cents per acre |
| 1939 | Confederated Tribes of the Chehalis adopt constitution and by-laws |
| 1940's-50's | Aberdeen's economy diversifies into plywood plants, furniture mills, paper mills, door factories, pulp mills, and chemical companies |
| 1941 | Nation's first tree farm dedicated - 120,000 acre Clemons Tree Farm near Montesano |
| 1950's | State orders removal of abandoned splash dams |
| 1951 | The Chehalis Tribe petitions the Indian Claims Commission for a claim against the United States for appropriated lands |
| 1959 | Developers buy 6,000 acres of uplands, beach, swamps, and ponds at Ocean Shores |
| 1962 | Descendants of the Upper and Lower Chehalis meet in Oakville to vote on a proposed settlement of the land claim |
| 1968 | Construction begins on 2 Satsop nuclear plants |
| 1970's | 15,000 acres in Capitol Forest acquired by state from Weyerhaeuser |
| 1971 | Centralia power plant constructed |
| 1972 | Columbia-Pacific RC&D formed |
| 1980 | Capitol Forest Management Plan - sustainable harvest on a 60-year rotation |
| 1983 | Work on Satsop nuclear plants is discontinued |
| 1984 | First meeting of the Chehalis Valley Historical Society |
| 1989 | Lady Washington - replica of Captain Grays brig - constructed |
| 1992 | Chehalis River Council formed |
| 1994 | Chehalis River Basin Land Trust formed |
This information provided courtesy of Washington Department of Ecology (DOE)