Washington State Route 221

state)">Washington, United States. The highway serves to connect the unincorporated community of Paterson to the county seat Prosser. The highway has existed since at least 1926 and was designated as Primary State Highway 8E from 1937 until the 1964 renumbering of Washington state highways.

State Route 221
Route information
Auxiliary route of SR 22
Maintained by WSDOT
Length	25.95 mi (41.76 km)
Existed	1964–present
Major junctions
North end	SR 22 at Prosser
South end	SR 14 at Paterson
Location
Country	United States
State	Washington
Counties	Benton
Highway system
State highways in Washington Interstate US State Scenic Pre-1964 1964 renumbering Former
← SR 215 → SR 223

SR 221 starts at an intersection with SR 14 in the unincorporated community of Paterson. After leaving Paterson the highway travels north through rural farm land as a two-lane highway. A few minor roads are intersected before the roadway turns to the west after about 17 mi (27 km), before turning back to the north. After the highway resumes its northerly course it climbs into the Horse Heaven Hills, gaining a passing lane through the uphill segments, before finally terminating at SR 22 in south Prosser.

Every year the Washington State Department of Transportation (WSDOT) conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of annual average daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2009, WSDOT calculated that as few as 2,000 cars traveled through the central part of the highway, and as many as 2,500 cars at the interchange with SR 22.

The roadway on its current alignment has existed since at least 1926, however there are records of a road between Paterson and Prosser since 1906. The highway was designated Secondary State Highway 8E (SSH 8E) in 1937, but the route number was changed to SR 221 during the 1964 state highway renumbering.

High winds have forced the closure of SR 221 in 2003, 2004, and 2005 due to large amounts of dust being blown around, causing visibility to drop to almost zero through the Horse Heaven Hills.

The entire highway is in Benton County.

Location	mi	km	Destinations	Notes
​	0.00	0.00	SR 14 – Pendleton, Vancouver
Prosser	25.95	41.76	SR 22 to I-82 – Mabton, Richland, Yakima
1.000 mi = 1.609 km; 1.000 km = 0.621 mi