What is Road signs in the United States?
[[File:Manual on Uniform Traffic Control Devices, December 2023 cover.png|thumb|right|11th edition of the MUTCD, published December 2023]] In the [[United States]], [[traffic sign|road signs]] are, for the most part, standardized by federal regulations, most notably in the ''[[Manual on Uniform Traffic Control Devices]]'' (MUTCD) and its companion volume the ''Standard Highway Signs'' (SHS). == Adoption and compliance == [[File:U.S. states by 2009 MUTCD adoption.svg|thumb|left|300px|Map showing state adoption of the 2009 edition of the ''Manual on Uniform Traffic Control Devices'':<br/>{{legend|#1b9e77|Adopted national MUTCD}} {{legend|#d95f02|Adopted national MUTCD with state supplement}} {{legend|#7570b3|Adopted state-specific MUTCD}}]] The 11th edition of the MUTCD was released on December 19, 2023.<ref>{{cite press release |url=https://www.transportation.gov/briefing-room/fhwa-releases-new-traffic-control-device-manual-updates-improve-safety-pedestrians |title=FHWA Releases New Traffic Control Device Manual with Updates to Improve Safety for Pedestrians, Bicyclists, and All Road Users |date=December 19, 2023 |access-date=December 27, 2023 |publisher=U.S. Department of Transportation}}</ref> The effective date, 30 days after publication, of the MUTCD was January 18, 2024. States have two years after the effective date to do one of the following options: adopt the revised MUTCD, adopt the revised MUTCD with a state supplement, or adopt a state-specific MUTCD.<ref>{{cite web |access-date=January 29, 2024 |title=Frequently Asked Questions - General Questions on the MUTCD |url=https://mutcd.fhwa.dot.gov/knowledge/faqs/faq_general.htm#stateq1 |website=MUTCD |publisher=Federal Highway Administration}}</ref> Eighteen states use the manual without alterations; 22 states, the [[District of Columbia]], and [[Puerto Rico]] have adopted it in conjunction with a supplemental volume; and ten states have a state version in substantial conformance to the MUTCD.<ref>{{cite web |title = MUTCDs & Traffic Control Devices Infor