Street Name Sign Buying Guide
MUTCD Street Name Sign Guidance
Section 2D.45 of the current MUTCD provides standards and guidance for Street Name signs (D3-1 and D3-1a), including lettering, size, color, and visibility. Here is what helps determine the sign you need.
Letter Height
Recommended minimum letter heights depend on how the sign is mounted, the type of roadway, and the posted speed limit.
Overhead signs — all roadway types and speeds
Initial upper-case: 12″
Lower-case: 9″
Post-mounted — multi-lane roadway over 40 mph
Initial upper-case: 8″
Lower-case: 6″
Post-mounted — multi-lane roadway 40 mph or less
Initial upper-case: 6″
Lower-case: 4.5″
Post-mounted — two-lane roadway
Initial upper-case: 6″
Lower-case: 4.5″
On two-lane local streets with speed limits of 25 mph or less, 4-inch initial upper-case letters with 3-inch lower-case letters may be used.
Engineering judgment may call for larger lettering based on the number of lanes on the approach, the length of turn lanes, whether advance street name signs are used, and how far the sign sits across the intersection.
Which Speed Limit Applies
The speed limit used to select letter height is that of the roadway the sign faces — not the street whose name appears on the sign.
For example, at an intersection of a 45 mph arterial and a 25 mph residential street, the sign naming the residential street faces the arterial and is sized for the 45 mph roadway.
Mixed-Case Lettering Is Required
Street names must use initial upper-case letters followed by lower-case letters.
All-capital street names do not meet the current standard, so replacement signs may not visually match older all-caps signs that are still in service.
Descriptors and Supplemental Legend
Street name descriptors such as St, Ave, or Rd, directional designations such as NW or SE, and other supplemental legend such as block numbers may be smaller than the street name itself.
Supplemental legend should be at least two-thirds of the street name’s letter height and should not be less than 3 inches for initial upper-case letters or 2.25 inches for lower-case letters.
MUTCD Sign Heights
Width varies with the length of the street name. MUTCD Table 2D-1 provides the following sign heights:
One-line Street Name sign
Conventional: 12″
Minimum: 8″
Oversized: 18″
Two-line Street Name sign
Conventional: 24″
Minimum: 15″
Oversized: 33″
Overhead Street Name sign
One line: 24″
Two lines: 48″
The reduced minimum sizes apply only in the limited circumstances permitted by Section 2A.07, including certain low-speed roadways, alleys, site roadways open to public travel, and qualifying low-volume rural roads.
Color
Green with white legend and border is the standard color combination.
Blue, brown, or white backgrounds are permitted alternatives for D3-1 and D3-1a Street Name signs where an agency uses color to indicate jurisdiction.
Green, blue, and brown backgrounds use white lettering and borders. White backgrounds use black lettering and borders.
If an alternative background color is used, it should generally be applied consistently to Street Name signs throughout that agency’s jurisdiction.
Advance Street Name signs (D3-2) must remain green.
Visibility
Street Name signs must be retroreflective or illuminated so they display the same general shape and color during both daytime and nighttime conditions.
Before You Order
Some states adopt their own MUTCD or publish state supplements containing additional or more restrictive requirements.
If you are purchasing Street Name signs for a public roadway, check your state and local agency requirements before ordering.
Reference: MUTCD 11th Edition with Revision 1 (December 2025), Section 2D.45, Table 2D-6, Table 2D-1, and Section 2A.07.
Street Name Signs Buying Guide – Frequently Asked Questions
What size letters do I need for a residential street sign?
For a post-mounted sign on a two-lane street, the recommended minimum is 6-inch initial upper-case letters with 4.5-inch lower-case letters.
On two-lane local streets with speed limits of 25 mph or less, 4-inch initial upper-case letters with 3-inch lower-case letters may be used.
Which speed limit determines the letter height?
Use the speed limit of the roadway the sign faces, not necessarily the street named on the sign.
For example, a sign naming a 25 mph side street that faces a 45 mph arterial is sized based on the 45 mph roadway.
Can Street Name signs be blue or white instead of green?
Yes. Blue, brown, and white are the permitted alternatives to green for D3-1 and D3-1a signs where an agency uses color to indicate jurisdiction.
Green, blue, and brown backgrounds use white lettering and borders. White backgrounds use black lettering and borders.
Advance Street Name signs (D3-2) must remain green.
Do Street Name signs have to use mixed-case lettering?
Yes. Street names must use initial upper-case letters followed by lower-case letters.
All-capital lettering does not meet the current standard for new Street Name signs.
What size sign blank do I need?
For conventional roads, MUTCD Table 2D-1 lists a one-line Street Name sign at 12 inches tall and a two-line sign at 24 inches tall.
Width varies based on the length of the street name and the required lettering.
Reduced heights of 8 inches and 15 inches are permitted only under the limited conditions described in Section 2A.07.