List of business routes of the Interstate Highway System

The Interstate Highway System of the United States, in addition to being a network of freeways, also includes a number of business routes assigned by the American Association of State Highway and Transportation Officials (AASHTO). These routes connect a central or commercial district of a city or town with an Interstate bypass.

Dwight D. Eisenhower National System of Interstate and Defense Highways
Interstate 24 Business marker
Interstate 196 Business marker
Highway shields for Business Loop Interstate 24 and Business Spur Interstate 196
Interstate Highways in the 48 contiguous states
System information
FormedJune 29, 1956[1]
Highway names
InterstatesInterstate nn (I-nn)
Business Loop:Business Loop Interstate nn (BL I-nn)
Interstate nn Business Loop (I-nn Bus. or I-nn BL)
Business Spur:Business Spur Interstate nn (BS I-nn)
Interstate nn Business Spur (I-nn Bus. or I-nn BS)
System links

As the main purpose of these routes are to serve a certain downtown area, business Interstates are typically routed along surface roads. These routes do not have to meet Interstate Highway standards and are not considered part of the Interstate Highway System. AASHTO does, however, apply similar standards as to new U.S. Highways, requiring a new business Interstate to meet certain design standards.[2]

Business Interstates are more commonly found in the western regions of the United States, as well as both across the Great Plains and in the state of Michigan. In contrast, Eastern states generally did not designate as many business Interstates. This geographic difference can be attributed to the way the Interstate Highway System was constructed in different parts of the country. In many eastern states, the new Interstates were often built to parallel the existing U.S. Highway network, rather than directly replacing those older routes. With the exception of mountainous areas, this left the majority of U.S. Highways intact, or co-signed routes with the Interstates. However, in the western states, the construction of the Interstate system more frequently involved directly overlaying the former U.S. Highway alignments. This sometimes left sections of the old U.S. Highways disconnected, especially in rural areas between cities and towns. To maintain access to those former highway segments, business Interstate designations were often applied as a way to guide drivers to key commercial districts and services. Although business Interstates are primarily found along primary Interstates, a few auxiliary Interstates also have their own business route designations.[citation needed]

Like auxiliary Interstates, business Interstates can be repeated from state to state along their route. The only difference is that business Interstates can also be repeated in several locations within the same state.

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Terminology and guidelines

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As the main purpose of these routes is to serve a certain downtown or urban area, business Interstates are typically routed along surface roads rather than limited-access freeway segments. This allows the business route to directly connect to and navigate a local street network, providing more accessible connections to the central business district. Business Interstates are often designated along existing city streets or arterials that already have a strong commercial and retail presence, rather than cutting through the urban core on a new alignment.

Since business Interstates are primarily routed along surface roads, they do not have to meet the strict design standards required for the mainline Interstate Highway System in order to qualify for that kind of designation. However, despite sharing the "Interstate" designation and similar shield design, business Interstates are not actually considered part of the mainline Interstate Highway System. They are treated more as auxiliary or supplemental routes that complement the overall Interstate network, rather than being fully integrated components.

The design standards for business Interstates are more akin to the guidelines used for new U.S. Highway routes. While they aim to maintain a baseline of safety and continuity, the standards are less stringent than the exacting specifications for lane widths, access control, grade separations, and other factors that define the main Interstate Highway network.[2]

Business route classifications

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Business Interstates are signed with green shields that visually resemble the standard Interstate Highway shield, but with a few key differences. The word BUSINESS is used instead of INTERSTATE, and, above the number, where the state name is sometimes included, the word LOOP or SPUR appears.

A business loop has both ends connected to its parent Interstate route. This allows the business loop to provide direct access to the central business district or other major destinations within a city or town. Many business loops were created to replace a decommissioned U.S. Route. One example includes all the I-5 business loops in northern California, which replaced US 99W through towns like Woodland, Arbuckle, or Williams. Sometimes, a business loop may either be cosigned with or supplement an active U.S. Route, such as I-70 Business Loop in Denver, Colorado, that follows US 40 and Colfax Avenue across the metropolitan area.

A business spur has one end connected to the parent Interstate route, while the other end dangles or terminates at a specific destination, often the downtown or central business district of a city or town. One example is Business Spur I-75 into Bay City, Michigan. Sometimes, a business spur originates from an Interstate's terminus and continues into the city/destination. An example of this is I-20 Business Spur into Florence, South Carolina, which originates from I-20's eastern terminus at I-95.

While most business Interstates are usually routed along surface roads, they are sometimes routed onto freeways. Some of these stretches of freeways were once designated as mainline Interstates themselves, such as I-85 Business Loop in Spartanburg, South Carolina, and I-80 Business Loop in Sacramento, California.

List

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Defunct routes are listed in italics.

Interstate 5

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Interstate 205

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Interstate 8

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Interstate 10

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Interstate 15

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Interstate 17

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Interstate 19

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Interstate 20

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Interstate 24

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Interstate 25

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Interstate 126

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Interstate 526

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Interstate 27

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Interstate 29

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Interstate 229

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Interstate 30

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Interstate 35

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Interstate 40

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Interstate 44

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Interstate 45

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Interstate 49

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Interstate 55

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Interstate 65

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Interstate 69

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Interstate 70

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Interstate 72

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Interstate 75

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Interstate 375

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Interstate 76 (west)

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Interstate 376

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Interstate 80

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Interstate 81

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Interstate 83

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Interstate 84 (east)

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Interstate 84 (west)

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Interstate 85

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Interstate 385

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Interstate 585

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Interstate 86 (west)

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Interstate 89

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Interstate 90

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Interstate 94

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Interstate 95

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Interstate 495

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Interstate 96

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Interstate 196

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Interstate 496

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Interstate 696

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See also

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Notes

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  1. ^ Downtown Loop I-24 in Paducah, Kentucky was changed to Business Loop I-24 in 2002.
  2. ^ Business Loop I-40 for Glenrio, Texas is a spur route (at the New Mexico state line it becomes a country road), but is posted as a business loop.

References

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  1. ^ Weingroff, Richard F. (Summer 1996). "Federal-Aid Highway Act of 1956, Creating the Interstate System". Public Roads. 60 (1). Washington, DC: Federal Highway Administration. Retrieved March 16, 2012.
  2. ^ a b Special Committee on U.S. Route Numbering (November 15, 1997). "Report of the Special Committee on U.S. Route Numbering to the Standing Committee on Highways" (PDF) (Report). Washington, DC: American Association of State Highway and Transportation Officials. Archived from the original (PDF) on October 16, 2017. Retrieved June 15, 2024.
  3. ^ District 11-0 (August 19, 2009). "I-376 Corridor New Exit Numbers" (PDF). Pennsylvania Department of Transportation. Retrieved November 21, 2009.{{cite web}}: CS1 maint: numeric names: authors list (link)[permanent dead link]


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