INTRODUCTION In order to bring some order out of route designation over the Nation@ the American Association of State Highway Officials (AASHO) in the early 20's requested the Secretary of Agriculture@ under whose offices the Bureau of Public Roads at that time operated@ to name a Committee for the purpose of formulating a plan or system of numbered highways@ principally for the assistance of motorists engaged in Interstate travel. Subsequent to that action@ this Association was asked by the Secretary of Agriculture to develop such a system. After much study and deliberation@ the system was developed and officially adopted in 1926@ and the administration and maintenance of records is kept in the offices of the American Association of State Highway and Transportation Officials@ as AASHO is now called. For the benefit of those reading this book who are not familiar with the organization of the AASHTO@ it is made up of the 50 State Highway and Transportation Departments@ the District of Columbia and Puerto Rico. In addition@ a number of public highway and transportation agencies in other nations belong to the Association as affiliate members@ and a number of substate transportation agencies in the United States belong as associate members. This system@ as it was initially laid out for all practical purposes@ is still in effect. It is administered by the Executive Committee of this Association. It is all a cooperative effort@ and stands as a monument to the several states in their adh-ence to the Purpose and Policy@ as adopted by the Association@ and revised in September 1970. Following this introduction in this book there appears this Purpose and Policy. Between the 1955 and 1969 editions@ the Executive Committee approved changes in the system. As a result@ the total mileage over all U.S. Numbered Routes in 1969 was 167@231 miles. In 1955@ this was 169@760. In 1974 it had been reduced to 163@198. it was further reduced in 1979 to 159@645. The mileage as of this book is 157@724 miles. It is of interest to note that beginning in 1955@ the Executive Committee@ which is the governing body of the AASHTO@ approved the use of a standard form for the purpose of submission of petitions in the matter of requesting changes in the given state. In view of the fact that the system@ as now established@ does not need extension but rather improvement@ the new form has been prepared with the idea of giving the maximum amount of information as to the traffic need and the road conditions to the Committee in order to better serve them in their deliberations. Specific attention is requested to the matter of supplemental routes. In the instance of alternate routes@ the parent route is broken at the point of beginning of the alternate route@ and the alternate route is inserted in the log. At the conclusion of the alternate route@ the parent route continues from the point the alternate route started and mention is made under the remarks column at the point the alternate route rejoins. Mileage on the alternate@ by-pass and business routes starts from zero. In the case of divided routes@ such as North and South@ or East and West@ the accumulated mileage from point of beginning of the route is based on the North Section or the West section. This information is noted on each route where it applies.