Colorado Highways:
County Road Numbering Systems

Highways in Colorado have one particularly unfortunate aspect: No uniformity in county road numbering. One of the reasons for this is governmental: Colorado has no townships, so any public road outside of city limits is a county road. This is different than, say, the Midwest, where the existence of townships causes only some rural roads to be county roads, allowing for development of a coherent statewide numbering system. But not in Colorado.

The county numbering systems that have evolved in Colorado vary from one to another of the 64 counties. There is no uniformity. What has happened in most counties is the rural, grid-based roads are numbered (or lettered) on what is called a geographical system, wherein the numbers increase from a starting point as one moves across the county, usually at one mile intervals for each section line. Some counties have even numbers east-west and odd numbers north-south, or numbers north-south and letters east-west. Again, there is no uniformity.

Generally, for the counties that do have a county road numbering systems, it is used for the rural, grid-based road system, while local roads through developments get street names. The most obvious exception to this is Mesa County, which uses the grid system also for local roads, resulting in odd fractions for roads that fall between section lines.

Route marker signs also vary from county to county. Where they exist, the markers usually take the form of the national standard blue pentagon, but there are exceptions. Some counties use green urban style street-name signs at intersections rather than separate route markers.

Main Source: Colorado Atlas & Gazetteer, DeLorme, 2000

Information Needed: Have info on county numbering practices, or photos of a county's route markers? Let me know!

Related Sites:

County
Numbering System
Route Markers
Marker Photos
Adams
No county road numbers. Uses metro Denver addressing:
E-W street numbers starting from 15th Ave. (Colfax Ave.) at south line increasing north (26th Ave. 1st mile, 38th Ave. 2nd mile, 48th Ave. 3rd mile, then 8 per mile) to 168th Ave. at north line.
N-S street names based on Denver system.
No markers; uses street name signs at intersections.

Alamosa
E-W: Based on 0 origin 5mi south of Mosca; Increasing 1 per mile, 1N, 2N, etc. to 12N at north line; 1S, 2S, etc. to 15S at south line.
N-S: Starts at 100 at west line, increasing east (1 per mile) to east line; N or S added in front for if it is north or south of origin (e.g. 102N, 106S).
Standard blue pentagon used in turn assemblies at intersections, also blue/yellow street names signs at intersections.

Arapahoe
Urban in metro: Only street names based on metro Denver system.

Rural: County roads have road numbers while some also have names.
E-W even starting from 2 at north line increasing south (4 per mile) to 50 at south line.
N-S odd starting from west line increasing (4 per mile) to above 285 at east line.
Standard blue pentagon, used generally as reassurance marker only. Street name signs at intersections.

Archuleta
Appears county roads have 3-digit road numbers. No known system for assigning them.
Unknown

Baca
E-W: Road letters starting from A at south line increasing north (1 per mile) to XX at north line (...X, Y, Z, AA, BB,...).
N-S: Road numbers starting from 0 at west line increasing east (1 per mile) to 57 at east line.
Street names signs at intersections.

Steve Riner
Bent
E-W: Road letters starting from A at south line increasing north (1 per mile) to WW at north line (...X, Y, Z, AA, BB,...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to 36 at east line.
Street name signs at intersections.

Steve Riner
Boulder
Plains portion: No county road numbers. E-W various street names; N-S street numbers from 1st St. origin in Boulder increasing east (8 per mile) to 128th St. at east line.

Mountains/foothills portion: Mixture of street names and road numbers. No known system to road numbers.
Most of county is street name signs at intersections. When a road number marker is used, it's a green square with white lettering, "BOULDER XX COUNTY".

Broomfield
Consolidated city-county. No county road numbers.


Chaffee
All country roads 3 digits.
E-W: Appears to start at approximately 100 at south line and increase (approximately 10 per mile) to north line.
N-S: No hard system discernible, other than increasing as heading west.

Geographic system does not necessarily give a road a hard number, instead provides a guide for approximately what it should be, i.e. if a road is in the 345 area of the grid it might be 340 or 342.
Standard blue pentagon, used as reassurance marker and in turn assemblies.

Cheyenne
E-W: Road letters starting from A at south line increasing north (1 per mile) to GG at north line (...X, Y, Z, AA, BB,...).
N-S: Road numbers starting from 0 at west line increasing east (1 per mile) to 60 at east line.
Unknown

Clear Creek
Generally county roads have street names. There are some road numbers; when used roads have 3-digit road numbers; no known system for assigning them.
Generally only street name signs at intersections used.

Conejos
E-W: Road letters starting from A at south line increasing north (1 per mile) to FF at north line (...X, Y, Z, AA, BB,...).
N-S: Road numbers starting from 1 at west edge of San Luis Valley increasing east (1 per mile) to above 28 at east line.
The few county roads in the San Juan Mountains in western part of the county have random 3-digit road numbers.
Road numbers on street name signs at intersections.
Costilla
E-W: Road letters starting from A at south line increasing north (1 per mile) to above SS at north line (...X, Y, Z, AA, BB,...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to above 29 at east line.
If a road falls between section lines a decimal is added (e.g. 11.5 is 5/10 of the way between 11 and 12).
Road numbers on street name signs at intersections.
Crowley
E-W: "ROAD" letters starting from A at south line increasing north (1 per mile) to above CC at north line (...X, Y, Z, AA, BB,...).
N-S: "LANE" numbers starting from 1 at west line increasing east (1 per mile) to 31 at east line.
If a road falls between section lines a decimal is added (e.g. F.5 is 5/10 of the way between F and G).
Road numbers on street name signs at intersections.
Custer
County road numbers are three digits; E-W even with 110s in south generally increasing to 190s in north; N-S odd generally increasing to the west.
Road numbers on street name signs at intersections.
Delta
E-W: Street names with the names starting with A in the south and increasing alphabetically toward the north.
N-S: Road numbers starting from 100 at east line increasing west (10 per mile) to 4600 at west line.

This system replaced what was in place prior to summer 2003. That system was E-W letters starting from A at south line increasing north (1 per mile) to above U at north line. N-S was numbers starting from 1 at west line increasing east (1 per mile) to above 44 at east line. (February 8, 2004 Denver Post)
Street name signs at intersections.

Denver
Consolidated city-county. No county road numbers.


Dolores
E-W: Road letters starting from A at north line increasing south (1 per mile) to above W at south line.
N-S: Road numbers starting from 0 at west line increasing east (1 per mile).
If a road falls between section lines a decimal is added (e.g. T.50 is 5/10 of the way between T and U).
Unknown

Douglas
All county roads have street names, but some also have road numbers assigned at random, but the only way you ever know about them is via reassurance markers.
Street name signs at intersecions. Marker is a pentagon, but green instead of blue. Used only as a reassurance marker.

Eagle
Generally county roads have street names. There are some road numbers; when used there is no known system for assigning them.
Generally only street name signs at intersections used, but scattered instances of blue pentagons for reassurance markers.

Elbert
E-W: Even numbers starting from 2 at south line increasing north (4 per mile) to 194 at north line.
N-S: Odd numbers starting from 1 at west line increasing east (4 per mile) to 205 at east line.
Diagonal roads get a hyphen combination of the grid lines it straddles (e.g. 61-69).
Standard blue pentagon, used generally as reassurance marker only. Road numbers on street name signs at intersections.

El Paso
No county road numbers. All roads have street names instead.
No markers; uses street name signs at intersections.

Fremont
No known system for placing road numbers, which are 1, 2, or 3 digits. Road numbers appear to be placed at random throughout county.
Green square with white lettering, used as reassurance marker. Also some street name signs with road numbers, which don't use prefixes or suffixes, just the number and nothing else.


Garfield
Road numbers are three digits. It appears 1xx are in area around Glenwood Springs, and for the rest of the county 2xx are north of I-70 and 3xx south of I-70. Within those systems numbers appear to be clustered together (e.g. 293 near 294 near 295). Many roads also have names.
Mainly street name signs at intersections. When a road has both a number and a name, both are shown on the same blade. Some scattered blue pentagons used as reassurance markers.


Gilpin
From maps it appears generally road numbers are 1- and low 2-digit numbers, with even E-W and odd N-S. However in the field, county roads appear to all be given street names with no numbers marked.
Brown street name signs at intersections.

Grand
Mixture of street names and road numbers. Road numbers are 1, 2, 3, or 4 digits. Appears to be no system for assigning them, although some are numbered as spurs (e.g. 553 branches off of 55).
Standard blue pentagon, used generally as reassurance marker only, but sometimes also for turn assemblies. Also street name signs at intersections, which may list both the street name and road number.

Gunnison
Road numbers are 1, 2, or 3 digits. Road numbers are assigned randomly throughout county.
Standard blue pentagon, used as reassurance marker and in some turn assemblies.

Hinsdale Road numbers are 1 or 2 digits. Road numbers appear to be assigned randomly throughout county. Unknown

Huerfano
Road numbers are 3 digits. It appears numbers are clustered together (e.g. 520 near 523 near 525).
Road numbers on street name signs at intersections.

Jackson
E-W: Even starting from 2 at north line increasing south to above 28.
N-S: Odd starting from 1 in west increasing to above 21.
Branches may be given letter suffixes (e.g. 26A and 26B branch off of 26).
Standard blue pentagon, used as reassurance marker only.

Jefferson
Most county roads have street names, but some have road numbers only (e.g. CR 73). Some have both street names and well known road numbers (e.g. Hogback Rd./CR 93).
Mixture. Some places it is standard blue pentagon, other places it is custom marker using the shape of the county. Street name signs at intersections.

Kiowa
E-W: Road letters starting from A at south line increasing north (1 per mile) to BB at north line (...X, Y, Z, AA, BB).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to 80 at east line.
Road numbers on street name signs at intersections.

Kit Carson
E-W: Road letters starting from A at south line increasing north (1 per mile) to RR at north line (...X, Y, Z, AA, BB...).
N-S: Road numbers starting from 0 at west line increasing east (1 per mile) to 60 at east line.
Road numbers on street name signs at intersections.

Lake
Mixture of street names and road numbers. Road numbers are 1 or 2 digits. Appears to be no system for assigning them. Standard blue pentagon, used generally as reassurance marker only.
La Plata
Road numbers are 3 digits. It appears numbers are clustered together (e.g. 311 near 313 near 314). Standard blue pentagon, used both in turn assemblies and as reassurance marker.

Larimer
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to above 80 at north line.
N-S: Odd numbers starting from 1 at east line increasing west (2 per mile) to above 103 at west line.
Roads between section lines use a letter suffix, i.e. 54G is 7/10 of the way between 54 and 56, G being the 7th letter in the alphabet.
Standard blue pentagon, used generally as reassurance marker only. Road numbers on street name signs at intersections, which may also have the block number.


Las Animas
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to above 100 at north line.
N-S: Odd numbers starting from 1 in west increasing east (2 per mile) to 227 at east line.
If a road falls between section lines a decimal is added (e.g. 12.5 is 5/10 of the way between 12 and 14).
Road numbers on street name signs at intersections. There are a few scattered blue pentagons.
Lincoln
E-W: Road letters starting from A at south line increasing north (1 per mile) to 4D at north line (...Z, 2A...2Z, 3A...3Z, 4A...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to 49 at east line.
CR 109 is special case where the county retained an SH number after the highway had been turned back.
Road numbers on street name signs at intersections. CR 109 has several white squares on turn assemblies. Also green squares as reassurance markers but very rare.


Logan
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to 78 at north line.
N-S: Odd numbers starting from 1 at west line increasing east (2 per mile) to 97 at east line.
If a road falls between section lines a decimal is added (e.g. 16.5 is 5/10 of the way between 16 and 18).
Green street name signs at intersections.

Mesa
E-W: From origin 3 miles south of downtown Grand Junction, road letters starting from A increasing north (1 per mile) to above X at north line; south of origin system is AS, BS, CS... to ZS, then Z1, Z2, Z3... to Z9 at south line.
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to above 71 at east line.
If a road falls between section lines a decimal is added (e.g. D.50 is 5/10 of the way between D and E). Mesa County is one of the few that also uses the grid-based system for local roads through developments, resulting in oddball decimals for some road names. There also is a mixture sometimes between decimals and fractions.
Street name signs at intersections. Roads in between section lines may be a decimal or a fraction depending on the sign.
Mineral
Very few county roads labeled in DeLorme. No discernible system.
Unknown

Moffat Road numbers are 1, 2, or 3 digits. Road numbers appear to be assigned randomly throughout county. Standard blue pentagon used as reassurance marker.

Montezuma
E-W: From origin 9 miles south of Cortez (north boundary of Ute Mountain Indian Reservation), road letters starting from A increasing north (1 per mile) to FF at north line (...Y, Z, AA, BB...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to above 44 in east.
Green steet name signs at intersections. Newer ones have "MCR XX". Red street name signs indicate private roads.

Montrose
Central Portion:
E-W: Road names with names starting with A in the north and going alphabetically (1 per mile) toward the south, e.g. Amber Rd, Banner Rd, Carnation Rd, etc.
N-S: Road numbers starting from west line increasing east (1 per mile) to above 80 in east.

Western and Far Eastern Portion:
E-W: Road numbers starting from north line increasing south (1 per mile) to JJ at south line (...Y, Z, AA, BB...). Many roads have number suffixes, e.g. DD19 and DD20 are separate roads both generally near the intersection of the DD and 19 grid lines.
Street name signs at intersections. Some areas of the county have newer signs with a logo.


Morgan
E-W: Road letters starting from A at south line increasing north (1 per mile) to KK at north line (...X, Y, Z, AA, BB...).
N-S: Road numbers starting from 0 at west line increasing east (1 per mile) to 36 at east line.
Road numbers on street name signs at intersections. Some have "RD xx", others "MCR xx".

Otero
E-W: Road letters starting from A at south line increasing north (1 per mile) to above MM at north line (...X, Y, Z, AA, BB...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to 37 at east line.
Street name signs at intersections.

Steve Riner

Ouray
Road numbers are 1 or 2 digits. Road numbers appear to be assigned randomly throughout county, except even are generally E-W and odd are N-S. Green square with white letters, used generally as reassurance marker.

Park
Road numbers are 1, 2, or 3 digits. Road numbers appear to be assigned randomly throughout county. Standard blue pentagon, used both in turn assemblies and as a reassurance marker.
Phillips
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to 44 at north line.
N-S: Odd numbers starting from 1 at west line increasing east (2 per mile) to 65 at east line.
If a road falls between section lines a decimal is added (e.g. 16.5 is 5/10 of the way between 16 and 18).
Green street name signs at intersections.
Pitkin
Road numbers are 1 to 3 digits. Road numbers appear to be assigned randomly throughout county, except even are generally E-W and odd are N-S. Many roads have names in addition to numbers. Street name signs at intersections. Some signs show both the name and number on the same blade.

Prowers
E-W: Road letters starting from A at south line increasing north (1 per mile) to WW at north line (...X, Y, Z, AA, BB...).
N-S: Road numbers starting from 1 at west line increasing east (1 per mile) to 39 at east line.
Street name signs at intersections.

Steve Riner
Pueblo
Mix of road names and numbers. Road names in the area immediately east of Pueblo use geographical system. Road numbers are 2, 3 or 4 digits and appear to be assigned randomly throughout county. Street name signs at intersections.


Rio Blanco
Road numbers are 1, 2, or 3 digits. Road numbers are assigned randomly throughout county. Standard blue pentagon, used both in turn assemblies and as reassurance markers.

Rio Grande
Valley Portion:
E-W: Based on 0 origin at Monte Vista; Increasing 1 per mile, 1N, 2N, etc. to 12N at north line; 1S, 2S, etc. to 12S at south line.
N-S: Based on 0 origin at US 285/SH 15; Increasing 1 per mile, 1E, 2E, etc. to 6E at east line; 1W, 2W, etc. to 7W near Del Norte.

Mountains Portion: Road numbers, low 2-digit numbers. No discernible system.
Standard blue pentagon, used in turn assemblies and as reassurance markers.

Routt
Road numbers are 1 or 2 digits. Road numbers appear to be assigned randomly. Green sqaure with white lettering, used as reassurance marker.

Saguache
E-W: Road letters starting from A at south line increasing north (1 per mile) to above XX at north line (...X, Y, Z, AA, BB...).
N-S: Road numbers starting from 1 in west increasing east (1 per mile) to above 71 at east line.
Diagonal roads get a hyphen combination of the grid lines it straddles (e.g. LL-57).
Standard blue pentagon, used in turn assemblies and as reassurance markers. Also scattered street name signs at intersections.

San Juan
A small, mountainous county, so there aren't all that many county roads. It appears generally road numbers are 1- and low 2-digit numbers. Standard blue pentagon.

San Miguel
E-W: Letter-Number, e.g. Q1, U29, with the letter coming from a grid that starts at A in the south and increases north, and the number from a grid that starts with 1 in the west and increases east.
N-S: Number.Letter, e.g. 43.Z, 6.H, with the same grid supplying the combination.
Unknown

Sedgwick
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to 36 at north line.
N-S: Odd numbers starting from 1 at west line increasing east (2 per mile) to 63.2 at east line.
If a road falls between section lines a decimal is added (e.g. 13.5 is 5/10 of the way between 13 and 15).
Green street name signs at intersections.
Summit
Mixture of street names and road numbers. Road numbers are 2 or 3 digits. Appears to be no system for assigning them. Street name signs at intersections. Sometimes the street name and road number is listed on the same one.

Teller
Mixture of street names and road numbers. Road numbers are 1, 2 or 3 digits, with no discernable system for 1 or 2 digits. 3 digits numbered as spurs off of another road number. Street names or road numbers on street name signs at intersections. Blue pentagons used here and there as reassurance markers.

Washington
E-W: Road numbers starting from 0 at south line increasing north (1 per mile) to 60 at north line.
N-S: Road letters starting from A at west line increasing east (1 per mile) to AAA at east line (...X, Y, Z, AA, BB...ZZ, AAA).
Road numbers on street name signs at intersections.

Weld
E-W: Even numbers starting from 2 at south line increasing north (2 per mile) to 140 at north line.
N-S: Odd numbers starting from 1 at west line increasing east (2 per mile) to 157 at east line.
Diagonal roads have 3-digit numbers starting with 3, e.g. 386, 390).
Standard blue pentagon, used generally as reassurance marker only. Road numbers on street name signs at intersections.
Yuma
E-W: Road numbers starting from 0 at south line increasing north (1 per mile) to 60 at north line.
N-S: Road letters starting from A at west line increasing east (1 per mile) to SS at east line (...X, Y, Z, AA, BB...).
If a road falls between section lines a decimal is added (e.g. 2.5 is 5/10 of the way between 2 and 3).
Road numbers on street name signs at intersections.

County
Numbering System
Route Markers
Marker Photos

Continue:

Page created 27 February 2004
Last updated 29 March 2014

Sig