Editing Interstate Highway System (section)

===Business routes===
{{multiple image
|align=right
|direction= horizontal
|width= 110
|image1= Business Loop 80.svg
|alt1= Business Loop Interstate 80 shield marker
|image2= Business Spur 80.svg
|alt2= Business Spur Interstate 80 shield marker
|header= Standard Interstate shields
|footer= Markers for Business Loop Interstate 80 (left) and Business Spur Interstate 80 (right)
}}
AASHTO defines a category of special routes separate from primary and auxiliary Interstate designations. These routes do not have to comply to Interstate construction or limited-access standards but are routes that may be identified and approved by the association. The same route marking policy applies to both US Numbered Highways and Interstate Highways; however, [[business route]] designations are sometimes used for Interstate Highways.<ref name="aashto_ho1">{{cite web |url = http://cms.transportation.org/sites/route/docs/HO1_Policy_Establ_Develop_USRN.pdf |title = Establishment and Development of United States Numbered Highways |date = January 2000 |access-date = January 23, 2008 |author = American Association of State Highway and Transportation Officials |publisher = American Association of State Highway and Transportation Officials |url-status = dead |archive-url = https://web.archive.org/web/20061101234239/http://cms.transportation.org/sites/route/docs/HO1_Policy_Establ_Develop_USRN.pdf |archive-date = November 1, 2006 }}</ref> Known as [[List of business routes of the Interstate Highway System|Business Loops and Business Spurs]], these routes principally travel through the corporate limits of a city, passing through the central business district when the regular route is directed around the city. They also use a green shield instead of the red and blue shield.<ref name="aashto_ho1" /> An example would be [[Interstate 75 Business (Pontiac, Michigan)|Business Loop Interstate 75]] at [[Pontiac, Michigan]], which follows surface roads into and through downtown. Sections of BL I-75's routing had been part of [[U.S. Route 10 in Michigan|US&nbsp;10]] and [[M-24 (Michigan highway)|M-24]], predecessors of [[Interstate 75 in Michigan|I-75]] in the area.