Montesano is a city in Grays Harbor County, Washington, United States. The population was 4,138 at the 2020 census. It is the county chair of Grays Harbor County.

According to Edwin Van Syckle, a allowance of the present-day town of Montesano was first platted in 1870 by Samuel Henry Williams, who purchased estate in what was known as Medcalf Prairie, named after the in the future settler William Medcalf. At not quite the same time, surveyor Charles Newton Byles bought a farm from Walter King on the present-day site of Montesano upon April 9, 1870, and progressive platted three blocks upon the west side of Main Street. The town of Montesano was born, but it was not incorporated until November 26, 1883, by the Washington Territorial Legislature.

Prior to that time, the name Montesano was used to tackle to the homestead of Isaiah Lancaster Scammon and his wife Lorinda. They filed a 640-acre Donation Land Claim on January 15, 1853, on the Chehalis River, opposite the mouth of the Wynoochee River, in the Place now referred to as South Montesano. The Scammon home was often referred to as “Scammon’s Landing” or “Scammon’s Hotel”, because it was an important stopping reduction along the Chehalis River for to the lead pioneers, and the furthest up-river mooring dwindling and railroad junction for seagoing ships.

According to Edmond S. Meany, in 1860 the seat of what was then called Chehalis County was moved to “the place of J.L. Scammons”. Mrs. Lorinda Scammon was certainly religious and wished to have the place named “Mount Zion”. Another further on settler, Samuel James, suggested “Montesano”, which was derived from Spanish meaning “mountain of health”; it was said that this had a more pleasant sound and designed about the same. The counsel was approved, and soon after, a state office was secured considering the name “Montesano”. The people of Chehalis County voted to fake the county seat to the platted town of Montesano in 1886, and the Scammon house was subsequently known as South Montesano.