posted along. If a local government maintains a numbered route, it signs an agreement with the state to keep the signs posted, thus keeping a continuous route for the benefit of travelers. History The initial primary state highway system was designated in 1917, initially consisting of 36 named and numbered highways, including some designated earlier that year by the Oregon State Legislature and others added to the network by the Oregon State Highway Commission, the predecessor to the OTC. The first signed routes were the U.S. Routes, in 1926. It was not until 1932 that Oregon Routes were numbered by the OTC and marked by the Oregon State Highway Department; every primary state highway that was not already part of a U.S. Route received a route number at that time. Starting in late 1931, the state took over maintenance of many county "market roads", which became secondary state highways with three-digit numbers; some of these were assigned route numbers in 1935, but many others remained unsigned. The primary, two-digit route numbers were laid out in a grid system, similar to the Interstate Highway System. Odd-numbered routes were north-south and increased in number bearing west, ranging from OR 3 in Wallowa County to OR 53 in Clatsop and Tillamook counties. Even-numbered routes were east-west and increased in number bearing south, ranging from OR 6 in Tillamook and Washington counties to OR 70 in Klamath County. East-west highways in eastern Oregon were given route numbers between OR 74 and OR 86, again increasing in number to the south. Despite this pattern, the internally used highway numbers for primary highways remained ad-hoc. A few route numbers were added after the 1930s, and broke these patterns for continuity reasons: OR 99, OR 126, OR 138, and OR 140. Secondary route numbers, three digits starting with 2, were laid out to generally increase bearing west. They ranged from OR 201 in Malheur County to OR 240 in Yamhill County. The internally used highway numbers for secondary highways were also three digit numbers, but were designated by county, from No. 10X in Clatsop County, No. 11X in Columbia County, No. 12X in Multnomah County, etc., until No. 45X in Malheur County. In 2002 and 2003, ODOT decided to assign route numbers to most of the previously unsigned secondary highways. Typically, these new route numbers were identical to the old highway numbers, and range from OR 103