Benton County is named for Thomas Hart Benton, who was a United States Senator from Missouri.
Surrounding County Courthouses:
N – Grant County
E – Franklin County and Walla Walla County
S – Umatilla County, Oregon and Morrow County, Oregon
W – Klickiat County and Yakima County
Created: March 8, 1905 
County Seat:
Prosser 1905 – present
County Courthouse – Prosser
Location: 620 Market Street / Main Street
Built: 1926 – 1927
Style: Classical Revival
Architect: Link & Rasquil of Spokane
Contractor: Ernst White & Company of Twin Falls, Idaho
Description: The building faces north and is a three story brown colored brick, terra cotta and concrete structure. The building is located on landscaped grounds in the center of Prosser. The north front has a large portico with two columns rising to the top of the second story, with a pediment above. The concrete foundation is covered with grey colored stucco. A wide horizontal white colored band runs below the first story windows and above the second story windows. A cornice runs below the roof line. The roof line is flat. Decorative features in the interior include terrazo flooring, oak banisters, doors, window and door surrounds; and moulded, plastered cornices. The courtroom is located at the northeast corner of the third story. The building houses the County Superior Court and the County District Court. An addition was constructed on the south sided in 1987. The architect was Ohashi-Augier Architects of Richland and the contractor was Lydig Construction Inc.
See: National Register of Historic Places – Benton County Courthouse
County Justice Center – Kennewick
Location: 7121 West Okanagan Place / West Quinault Avenue
Built: 2001 – 2003
Style: Modern
Architect: Ohashi-Augier Architects and Planners of Richland and Hummel Architects of Boise, Idaho
Contractor: Garco Construction Inc. of Spokane
Description: The building faces east and is a two story cream colored concrete and glass structure. The building is located on spacious grounds on the northwest side of the Justice Center Complex to the northwest of the center of Kennewick. The east front has a high concrete wall with recessed entrance on the east side. The windows are horizontal and recessed. The roof line is flat. The building houses the County Superior Court and the County District Court for Benton County and Franklin County.
Note: The Justice Center has three buildings with the Court Building A ( 2001 ) on the northwest, Sheriff’s Office Building B ( 1984 ) on the northeast and the Jail ( 1984 ) along the south. Construction and renovation costs in 2001 were $29,730,000.
County Juvenile Justice Center – Kennewick
Location: 5606 West Canal Drive / North Grant Street
Built: 1978 – 1979
Style: Modern
Architect: Carson & Kesterson
Contractor: Gilbert H Moen
Description: The building faces south and is a one story buff colored concrete structure. The building is located on landscaped grounds to the northwest of the center of Kennewick and is “U” shaped. The recessed entrance is located at the southeast corner. The windows are horizontal and the roof line is flat. The building is named for James J Lawlass and serves Benton County and Franklin County.
See: The Judicial District includes Franklin County.
History: The county was created in 1905 and Prosser was selected as the county seat. The first courthouse in 1905 was the Riverside Hotel built in 1887. From 1907 to 1919 the county occupied offices in the Viles Block on Seventh Street. The second courthouse was built in 1905. The cost of construction of the third and present courthouse in 1926 to 1927 was $87,000. The bid of Ernst White & Company of Twin Falls, Idaho was $75,321. George Rasque of Wisconsin headed the construction project. The County Juvenile Justice Center was constructed in Kennewick in 1978 yo 1979. The County Justice Center was constructed in Kennewick in 2001 to 2003.
County Courthouse – Prosser
Picture 1905 First County Courthouse
County Justice Centwer – Kennewick
County Juvenile Justise Center – Kennewick
Photos taken 2009 and 2016