MUTCD Street Name Sign Guidance

Choosing the right street name sign involves both the height of the blade and the size of its lettering. Our standard signs come on 6″ and 9″ blades for different private-property and roadway applications. For signs installed on roads open to public travel, confirm the finished design with the responsible road authority before ordering.

Which Blade Do I Need?

9″ Street Name Signs

Our 9″ blade provides room for larger lettering and greater visibility. It accommodates approximately 6″ initial upper-case letters and 4.5″ lower-case letters, corresponding to MUTCD recommended minimum letter heights for post-mounted signs facing:

• Two-lane roadways
• Multilane roadways with speed limits of 40 mph or less

Ordering for a public roadway? Letter height and blade height are separate considerations. The MUTCD lists a 12″ conventional height for a one-line street name sign; use of a smaller blade depends on the location and conditions. Confirm the required dimensions and finished lettering with the road authority.

6″ Street Name Signs

Our 6″ blade accommodates approximately 4″ initial upper-case letters and 3″ lower-case letters. It is a compact choice for identification and wayfinding where an MUTCD D3-1 roadway sign is not required. Depending on access and local rules, examples may include private-property drives, parking areas, and roads within properties where public access is restricted at all times.

The MUTCD permits 4″/3″ lettering on certain two-lane local roads with speed limits of 25 mph or less. That letter-size allowance does not make a 6″ blade an MUTCD-size roadway sign: Table 2D-1 lists 8″ as the minimum height for a one-line post-mounted D3-1 sign.

Larger & Special-Size Signs

Contact us if your project calls for a 12″ blade, larger lettering, an overhead or two-line sign, block numbers, or an agency-specified layout. Send us the agency’s specifications, and we can help identify a sign configuration that matches them.

Recommended Minimum Letter Heights

MUTCD Section 2D.45 and Table 2D-6 give the following recommended minimum heights for the street name lettering:

Larger lettering may be appropriate depending on the approach lanes, turn lanes, use of advance street name signs, and viewing distance across the intersection.

Letter Size vs. Blade Size

A blade’s height is its overall sign height; letter height measures the lettering on its face. For a one-line post-mounted D3-1 or D3-1a street name sign, MUTCD Table 2D-1 lists:

The smaller minimum size is limited to qualifying locations and conditions. A 9″ blade can accommodate the recommended 6″/4.5″ lettering, but its use as a roadway sign still calls for a separate blade-size and design check.

Which Speed Limit Applies?

Use the speed limit of the roadway the sign faces, which may differ from the street named on the sign.

For example, if a blade names a quiet side street but faces traffic on a two-lane 45 mph road, the recommended 6″ initial upper-case and 4.5″ lower-case lettering applies. Check the required blade size separately.

Where and How to Mount Street Name Signs

In residential areas, MUTCD guidance calls for at least one street name sign at each intersection. In business and commercial areas and on principal arterial roads, signs should be placed on at least diagonally opposite corners. Signs should identify both intersecting streets.

Mount each blade with its face parallel to the street it names. The MUTCD recommends lettering on both sides to help pedestrians navigate. A street name sign may be mounted above a STOP, YIELD, or other regulatory sign on the same support without a required vertical gap.

For mounting heights, distance from the road, and post requirements, see our Traffic Sign Installation Guidelines.

Mixed-Case Lettering

The MUTCD requires street names to use initial upper-case letters with lower-case letters:

Oak Ridge ✓
OAK RIDGE ✗

A new sign may therefore look different from an older all-capital sign still in service.

Street Name Sign Colors

Green with white lettering is the standard street name sign color combination. The MUTCD also permits blue or brown backgrounds with white lettering, or a white background with black lettering, under its provisions for alternative colors selected by the highway agency.

Our standard line offers green with white, blue with white, and white with black. Advance Street Name signs (D3-2) have separate rules and use green with white lettering.

Reflectivity & Nighttime Visibility

Street name signs used on roadways must be retroreflective or illuminated for nighttime visibility. Our street name signs include High Intensity Prismatic (HIP) retroreflective sheeting.

Before You Order

For a public roadway, municipal project, or other regulated installation, verify the blade size, finished letter heights, colors, and other specifications with the responsible agency before placing your order.

If you have the agency’s specifications and need help matching them to a product, contact us.

Frequently Asked Questions

What size street name sign do I need for a residential street?

For a post-mounted sign facing a two-lane road, the MUTCD recommends 6″ initial upper-case and 4.5″ lower-case lettering. On certain two-lane local roads at 25 mph or less, 4″/3″ lettering is permitted. Blade height is a separate check: the conventional one-line D3-1 sign is 12″ high, with an 8″ minimum available under qualifying conditions. Confirm the required finished sign with the road authority.

Which speed limit determines the letter size?

The speed limit of the roadway the sign faces, rather than necessarily the street named on the blade.

Can I use a 6″ blade on a public road?

Generally, no. A 6″ blade is below the 8″ minimum height listed for a one-line D3-1 street name sign in MUTCD Table 2D-1. The MUTCD contains a narrow smaller-size exception for certain alleys with restrictive conditions, so the road authority should determine whether any exception applies.

Do street name signs have to use mixed-case lettering?

Yes. The MUTCD requires street names on D3-1 signs to use initial upper-case letters with lower-case letters, such as “Oak Ridge” rather than “OAK RIDGE.”

Reference: Manual on Uniform Traffic Control Devices, 11th Edition with Revision 1, Sections 2A.07 and 2D.45; Tables 2D-1 and 2D-6.