Editing Interstate Highway System (section)

===Interstate shield===
[[File:Texas interstate shield proposals.jpg|thumb|Several Interstate shield design proposals submitted by the Texas Highway Department|alt=Three black and white submissions, the third being similar to the modern Interstate Highway shield]]

Interstate Highways are signed by a number placed on a red, white, and blue [[Highway shield|sign]]. The shield design itself is a [[registered trademark]] of the [[American Association of State Highway and Transportation Officials]].<ref>{{cite web |url = http://tsdr.uspto.gov/#caseNumber=72239199&caseType=SERIAL_NO&searchType=statusSearch |author = American Association of State Highway Officials |date = September 19, 1967 |title = Trademark Registration 0835635 |work = Trademark Electronic Search System |publisher = [[United States Patent and Trademark Office]] |access-date = April 27, 2014 |archive-url = https://web.archive.org/web/20130502074700/http://tsdr.uspto.gov/#caseNumber=72239199&caseType=SERIAL_NO&searchType=statusSearch |archive-date = May 2, 2013 |url-status = dead }}</ref> The colors red, white, and blue were chosen because they are the colors of the [[Flag of the United States|American flag]]. In the original design, the name of the state was displayed above the highway number, but in many states, this area is now left blank, allowing for the printing of larger and more-legible digits. Signs with the shield alone are placed periodically throughout each Interstate as [[reassurance marker]]s. These signs usually measure {{convert|36|in|cm}} high, and are {{convert|36|in|cm}} wide for two-digit Interstates or {{convert|45|in|cm}} for three-digit Interstates.<ref name="SHS">{{Cite book |author = Federal Highway Administration |chapter-url = https://mutcd.fhwa.dot.gov/SHSe/Guide.pdf |chapter = Guide Signs |title = Standard Highway Signs |edition = 2004 English |location = Washington, DC |publisher = Federal Highway Administration |oclc = 69678912 |orig-year = 2004 |date = May 10, 2005 |at = pp. 3-1 to 3-3 |access-date = February 22, 2012 |archive-date = February 5, 2012 |archive-url = https://web.archive.org/web/20120205020037/http://mutcd.fhwa.dot.gov/SHSe/Guide.pdf |url-status = live }}</ref>

Interstate business loops and spurs use a special shield in which the red and blue are replaced with green, the word "BUSINESS" appears instead of "INTERSTATE", and the word "SPUR" or "LOOP" usually appears above the number.<ref name="SHS" /> The green shield is employed to mark the main route through a city's central business district, which intersects the associated Interstate at one (spur) or both (loop) ends of the business route. The route usually traverses the main thoroughfare(s) of the city's downtown area or other major business district.<ref name="MUTCD2D">{{cite book |author = Federal Highway Administration |date = December 2009 |chapter = Chapter 2D. Guide Signs: Conventional Roads |title = Manual on Uniform Traffic Control Devices |chapter-url = https://mutcd.fhwa.dot.gov/pdfs/2009/part2d.pdf |page = 142 |location = Washington, DC |publisher = Federal Highway Administration |oclc = 496147812 |edition = 2009 |title-link = Manual on Uniform Traffic Control Devices |access-date = February 22, 2012 |archive-date = March 15, 2012 |archive-url = https://web.archive.org/web/20120315132420/http://mutcd.fhwa.dot.gov/pdfs/2009/part2d.pdf |url-status = live }}</ref> A city may have more than one Interstate-derived business route, depending on the number of Interstates passing through a city and the number of significant business districts therein.<ref name="MDOT11">{{cite MDOT map |year= 2011 |inset= Lansing |link= yes }}</ref>

Over time, the design of the Interstate shield has changed. In 1957 the Interstate shield designed by [[Texas Highway Department]] employee Richard Oliver was introduced, the winner of a contest that included 100&nbsp;entries;<ref>{{cite magazine |author = Texas Transportation Institute |url = http://tti.tamu.edu/publications/researcher/v41n4/41_4.pdf |title = Ties to Texas |magazine = Texas Transportation Researcher |volume = 41 |issue = 4 |pages = 20–21 |year = 2005 |archive-url = https://web.archive.org/web/20100820082038/http://tti.tamu.edu/publications/researcher/v41n4/41_4.pdf |archive-date = August 20, 2010 |author-link = Texas Transportation Institute }}</ref><ref>{{cite web |author = American Association of State Highway and Transportation Officials |year = 2006 |url = http://www.interstate50th.org/gallery.shtml |title = Image Gallery |work = The Interstate is 50 |publisher = American Association of State Highway and Transportation Officials |access-date = February 22, 2012 |url-status = dead |archive-url = https://web.archive.org/web/20120225170530/http://www.interstate50th.org/gallery.shtml |archive-date = February 25, 2012 }}</ref> at the time, the shield color was a dark navy blue and only {{convert|17|in|cm}} wide.<ref>{{cite book |author = American Association of State Highway Officials |year = 1958 |title = Manual for Signing and Pavement Marking of the National System of Interstate and Defense Highways |location = Washington, DC |publisher = American Association of State Highway Officials |oclc = 3332302 }}</ref> The ''[[Manual on Uniform Traffic Control Devices]]'' (MUTCD) standards revised the shield in the 1961,<ref name="MUTDC61">{{cite book |author1 = National Joint Committee on Uniform Traffic Control Devices |author2 = American Association of State Highway Officials |year = 1961 |chapter = Part&nbsp;1: Signs |chapter-url = http://www.trafficsign.us/oldmutcd/1961/1-signs.pdf |title = Manual on Uniform Traffic Control Devices for Streets and Highways |edition = 1961 |location = Washington, DC |publisher = Bureau of Public Roads |pages = 79–80 |oclc = 35841771 |access-date = February 22, 2012 |archive-date = April 14, 2012 |archive-url = https://web.archive.org/web/20120414190819/http://www.trafficsign.us/oldmutcd/1961/1-signs.pdf |url-status = live }}</ref> 1971,<ref name="MUTDC71">{{cite book |author1 = National Joint Committee on Uniform Traffic Control Devices |author2 = American Association of State Highway Officials |year = 1971 |chapter = Chapter&nbsp; 2D. Guide Signs: Conventional Roads |chapter-url = http://www.trafficsign.us/oldmutcd/1971/2d-guidesignsconv.pdf |title = Manual on Uniform Traffic Control Devices for Streets and Highways |edition = 1971 |location = Washington, DC |publisher = Federal Highway Administration |page = 88 |oclc = 221570 |access-date = February 22, 2012 |archive-date = November 29, 2011 |archive-url = https://web.archive.org/web/20111129185358/http://trafficsign.us/oldmutcd/1971/2d-guidesignsconv.pdf |url-status = live }}</ref> and 1978<ref name="MUTDC78">{{cite book |author = National Advisory Committee on Uniform Traffic Control Devices |year = 1978 |chapter = Chapter&nbsp; 2D. Guide Signs: Conventional Roads |chapter-url = http://www.trafficsign.us/oldmutcd/1978/2d-guidesigns.pdf |title = Manual on Uniform Traffic Control Devices for Streets and Highways |edition = 1978 |location = Washington, DC |publisher = Federal Highway Administration |page = ((2D-5)) |oclc = 23043094 |access-date = February 22, 2012 |archive-date = November 29, 2011 |archive-url = https://web.archive.org/web/20111129165921/http://trafficsign.us/oldmutcd/1978/2d-guidesigns.pdf |url-status = live }}</ref> editions.