U.S. Highways : From US 1 to (US 830) www.us-highways.com by Robert V. Droz

Numbering Convention for United States Numbered Highways

The U.S. Numbered Highway System is not a true Federal program of roadways. It is a series of interconnected state highways with a common numbering plan established for the purpose of aiding navigation. US Numbered Highways are built and maintained by the individual states, and funded in the same manner as any other state highway - usually with Federal funds. In most states, US Highways are simply State Highways with a different shield. Numbering and signing of US Routes is affirmed by the American Association of State Highway and Transportation Officers (AASHTO). Participation in the US route system is voluntary. States are not bound by Federal law to comply with US route designations, nor is there any penalty for non-compliance.

• US routes are all in the contiguous 48 states and have 1, 2, or 3 digit numbers
  • Even numbers run east to west; increasing to the south
    • Principal routes are one or two digits (abbreviated as 2dus) and end in 0: US 10 to US 90
    • Existing range is US 2 to US 98
  • Odd numbers run north to south; increasing to the west
    • Principal routes are one or two digits (with a single three digit exception) and end in 1: US 1 to US 101
    • Existing range is US 1 to US 101
  • Increments of low-order digits fill in the grid
    • e.g. US 20, US 22, US 24, ... US 30 - Even Numbered
    • e.g. US 21, US 23, US 25, ... US 31 - Odd Numbered
  • In addition, an increment of 3rd high order digits (3dus) denote branch highways or spur routes.
    • e.g. US 166, US 266, (US 366), (US 466), (US 566), (US 666)
  • US Divided-number Routes are of the form nd where d is {N|S|E|W}
    • e.g. US 70N, US 70S and (US 99E), (US 99W).

• In 1970, AASHTO revised its guidelines for US highways.
  • No new divided (split) US route numbers; Existing ones should be eliminated.
  • No new US numbers for routes wholly in a single state.
  • Existing single state US routes < 300 miles long should be eliminated.

Additionally, auxilliary signs further define the US Highways ...
Sometimes these banners are signed as suffixes, like US 89A which means Alternate US 89
Cardinal directions, such as -WEST- are usually placed above the shield.
The following banners indicate additions to the US Highway system

• ALTERNATE ALT (OPTIONAL) (OPT) : a longer or less well constructed loop along the main route which would have been suitable as the mainline if a better route was not available. OPT is an old name for this type.
• BUSINESS BUS (CITY) : a loop leading through the heart of a city's commercial area, generally the original route though town. City is the older name for the type.
• BYPASS BYP RELIEF (BELT LINE) : a loop leading around the heart of a city's commercial / most congested area, generally more recently built. BELT LINE is an older little-used name for the type.
• DETOUR : an interim route used while the main route is under construction. Usually used for mainline traffic. Uses an orange banner.
• HISTORIC OLD FORMER : previous alignments, not recognized by AASHTO.
• SCENIC : a little used subset of ALT.
• SPUR CONNECTOR CONN : a branch route connecting to a specific location along the road. Connector routes, a subset of the type, have been appearing recently
• TEMPORARY TEMP : an interim route used while the main route is under initial construction, or when the proposed routing is not yet finalized. Used for mainline traffic.
• TOLL : a route loop you have to pay to drive on. Rarely used with US routes, there is supposed to be a free US signed alternative.
• TRUCK : a subset of Bypass meant for trucks and other large vehicles.

The Big Table Notes:

1. Routes in the following table are listed odd numbers first, then even, with 'branch' routes listed afterwards.
2. Routes listed in parentheses - e.g. (US 830) - represent Decommissioned / Former / Historic / Old routes
3. The /N//S//E//W/ in the Notes column refers to the existence, past or present, of Divided (Split) Routes
4. Lengths are given in miles, both current and (historical maximum).
5. In From / To : * stands for International border, - stands for state line, ~ stands for ferry dock, and + stands for nearby road junction.

Last update to this page on Thursday, September 30, 2004

E-mail : us98 @ earthlink.net

All the information on this page is duplicated elsewhere on the site.

The basic format of this page is a tribute to the original JPGS US highways site.

www.us-highways.com