アメリカ合衆国の道路標識
規制標識
規制標識（regulatory sign）はMUTCD及び各州令においてR類に区分されるもので、一時停止や駐車禁止などの規制事項を示す。対象は自動車類（オートバイ等も含む。以下同じ）及び歩行者、自転車である。
実情にあわせ、州令により地域独自の規制標識が設定されている場合がある。また、整理番号の末尾にPがつくものは補助標識に相当するもので、単独では用いられない。
駐車・停留・停車
駐車禁止（No Parking）は、人の乗降の有無を問わず一時的な停車は許可されるが、駐車については禁止するものである。停留禁止（No Standing）は、駐停車のいずれも禁止するが、人の乗降を伴うもののみ許可するものである。停車禁止（No Parking）は一切の停車を禁じるもので、標識、信号、交通整理員、警察官の指示に従う場合および危険を回避する場合を除き、停車することはできない。 
標識内の矢印は規制が適用される路肩を指している。
学校標識
学校に関連する標識については、MUTCDによりS類として設定されている。蛍光黄緑色が用いられる。
警戒標識
警戒標識（Warning sign）はMUTCD及び各州令においてW類に区分されるもので、カーブや行き止まりなどの道路状況のほか、ハンプや緊急車両、道路工事などに関する注意を促すものである。一部を除き菱形で、黄色または蛍光黄色が用いられ、補助標識と併用される。
実情にあわせ、地域独自の規制標識が州令により設定されている場合がある。
交差点
MUTCDでは交差点（ロータリーを含む）に対する警戒標識をW2類として定めている。全ての交差点形状に対応できないため、独自でMUTCDにない様式を定めている州もある。
交通規制
MUTCDでは最高速度や信号機などの交通規制に関する予告をW3類として定めている。MUTCDだけではあらゆる状況に対応できていないため、独自の基準を定めている州も存在する。
車線・合流
The MUTCD's W4 series of signs is for warning signs relating to advance traffic controls such as speed limits and signals. As all situations are not covered, several states have their own standards in addition to the MUTCD.
幅員
The MUTCD's W5 series of signs is for warning signs relating to road width restrictions. As all situations are not covered, several states have their own standards in addition to the MUTCD. The MUTCD provides options for graphic and text signs.
中央分離帯
The MUTCD's W6 series of signs is for warning signs relating to divided highways. As all situations are not covered, several states have their own standards in addition to the MUTCD. The MUTCD provides options for graphic and text signs.
舗装・道路状況
The MUTCD's W8 series of signs is for warning signs relating to pavement and roadway conditions. As all situations are not covered, several states have their own standards in addition to the MUTCD.
車線関係
The MUTCD's W9 series of signs is for warning signs relating to lane transitions. As all situations are not covered, several states have their own standards in addition to the MUTCD.
踏切・路面電車関係
The MUTCD's W10 series of signs is for warning signs relating to rail and light rail. As all situations are not covered, several states have their own standards in addition to the MUTCD.
車両出入・横断関係
The MUTCD's W11 series of signs is for warning signs relating to advance warnings and crossings. As all situations are not covered, several states have their own standards in addition to the MUTCD. The MUTCD allows use of a fluorescent yellow-green background color for signs relating to people crossing the road.
緊急車両
The MUTCD only provides for a warning of fire stations in the W11 series. Most states have their own signs for other emergency vehicle types which may enter the road.
児童
The MUTCD specifies no children related signs in the W11 series. Several states, counties, and municipalities have signs for situations as children at play as well as children with various medical conditions. Some of these signs vary from state to state as there is no federal standard.
自転車
The MUTCD provides several signs in the W11 series warning of bicycles and for signing bicycle facilities. Several states and localities have their own specific bicycle related signs as well.
車両
The MUTCD provides several signs in the W11 series dealing with vehicles. Several states have additional signs for other types of vehicles and situations regarding vehicles not covered by the MUTCD.
歩行者・路面電車・航空機
The MUTCD provides several signs in the W11 series dealing with pedestrians, transit, and aviation. Several states have additional signs for other types of vehicles and situations regarding vehicles not covered by the MUTCD.
動物
The MUTCD provides several signs in the W11 series dealing with animals. Several states have additional signs for other types of animals not covered by the MUTCD.
車庫・出入口
The MUTCD does not provide signs in the W11 series dealing with driveways and entrances. Many states have their own sign standards dealing with these situations that they place in their own W11 series.
高さ制限
The MUTCD's W12 series of signs is for warning signs relating to low clearances. As all situations are not covered, several states have their own standards in addition to the MUTCD.
安全速度
The MUTCD's W13 series of signs is for warning signs relating to advisory speeds. As all situations are not covered, several states have their own standards in addition to the MUTCD.
行き止まり・追越し禁止
The MUTCD's W14 series of signs is for warning signs relating to dead end streets and no passing zones. As all situations are not covered, several states and local governments have additional signs for other types of situations not covered by the MUTCD.
児童公園
The MUTCD's W15 series of signs is for warning signs relating to playgrounds. As all situations are not covered, several states have their own standards in addition to the MUTCD.
補助板
The MUTCD's W16 series of signs is for supplemental plaques for warning signs. As all situations are not covered, several states have their own standards in addition to the MUTCD.
速度抑制ハンプ
The MUTCD's W17 series of signs is for warning signs relating to speed humps. As all situations are not covered, several states have their own standards in addition to the MUTCD.
出入制限解除
The MUTCD's W19 series of signs is for warning signs relating to the end of a controlled access highway. As all situations are not covered, several states have their own standards in addition to the MUTCD.
W20 Series: Work Zones
The MUTCD's W20 series of signs is for warning signs relating to work zones. These signs are typically orange background ones used for temporary situations. As all situations are not covered, several states have their own standards in addition to the MUTCD.
バリケード
The MUTCD barricades alert drivers that the road is closed, these signs are white.
道路工事中
The MUTCD's W21 series of signs is for warning signs relating to road work. These signs are typically orange background ones used for temporary situations. As all situations are not covered, several states have their own standards in addition to the MUTCD.
発破作業中
The MUTCD's W22 series of signs is for warning signs relating to blasting zones. These signs are typically orange background ones used for temporary situations. As all situations are not covered, several states have their own standards in addition to the MUTCD.
低速交通
The MUTCD's W23 series of signs is for warning signs relating to slow traffic. These signs are typically orange background ones used for temporary situations. As all situations are not covered, several states have their own standards in addition to the MUTCD.
車線遷移
The MUTCD's W24 series of signs is for warning signs relating to lane shifts, where traffic I'd diverted slightly toward the left or right of the roadway, but the route is otherwise unchanged. These signs are typically orange background ones used for temporary situations. As all situations are not covered, several states have their own standards in addition to the MUTCD.
W25 Series: Oncoming Traffic Has Extended Green
The MUTCD's W25 series of signs is for warning signs oncoming traffic having an extended green signal at a traffic light. As all situations are not covered, several states have their own standards in addition to the MUTCD.
その他
The MUTCD does not provide signs dealing with some other road and highway situations. Many states have their own sign standards dealing with these situations.
案内標識
案内標識には高速道路での路線番号案内標識、通り名、距離標、出口案内標識が含まれる。
路線番号標識
路線番号標識は通称「シールドマーカー」とも呼ばれている。
Note: State markers are illustrative examples; all states may select their own marker shapes or use the default circle. See Numbered highways in the United States#State highways and other similar systems.
案内標識（有料道路）
Chapter 2F of the MUTCD deals with signs for toll roads.
MUTCD非対応標識
MUTCDでは規定されていない公道・準公道での標識が存在する地域がある。
その他
これらの標識は既に廃止されているが、今でも見かけることがある。