Washington State Route 300

State Route 300 (SR 300) is a short state highway in Mason County, in the U.S. state of Washington. It extends 3.35 miles (5.39 km) from Belfair State Park to SR 3 in the community of Belfair. The route serves as a connector from Belfair State Park to Belfair and SR 3. The highway was Secondary State Highway 21C (SSH 21C) from 1957 until 1964.

State Route 300
Map of Mason County in western Washington with SR 300 highlighted in red
Route information
Auxiliary route of SR 3
Maintained by WSDOT
Length	3.35 mi[1] (5.39 km)
Existed	1964[2]–present
Major junctions
West end	Belfair State Park
East end	SR 3 in Belfair
Location
Country	United States
State	Washington
Counties	Mason
Highway system
State highways in Washington Interstate US State Scenic Pre-1964 1964 renumbering Former
← SR 292 → SR 302

Route description

SR 300 runs 3.35 miles (5.39 km) from Belfair State Park to SR 3 in the community of Belfair. The route serves as a connector from Belfair State Park to Belfair and SR 3.^[3][4] WSDOT has found that more than 11,000 motorists utilize the road daily before the interchange with SR 3 based on annual average daily traffic (AADT) data.^[5] SR 300 starts at the entrance to Belfair State Park west of Belfair. From the state park, the highway goes northeast along the coastline of the Hood Canal to Belfair, and turns south to merge onto SR 3.^[3][6]

History

The shield of SSH 21C

When the Primary and Secondary Highways were realigned in 1957, the current SR 300 became Secondary State Highway 21C (SSH 21C).^[7] SSH 21C became SR 300 in 1964 during the 1964 highway renumbering, in which the Washington State Department of Transportation (WSDOT) replaced the previous system of Primary and Secondary Highways with a new system called State Routes, which is still in use today.^[8][9]

Major intersections

The entire route is in Mason County.

Location	mi[1]	km	Destinations	Notes
​	0.00	0.00	Belfair State Park
Belfair	3.35	5.39	SR 3 – Bremerton, Shelton
1.000 mi = 1.609 km; 1.000 km = 0.621 mi