United States Geologic Service (USGS) Topographic Map Key (Legend)
Interpreting the colored lines, areas and other symbols is necessary in using the topographic maps. The USGS Topographic Maps use symbols or colors to represent features, and this Topographic Map Key explains what they mean.
Contour lines are distinctive to the topographic maps but there are other features shown on the maps including buildings, water and vegetation. In fact, there are nearly 200 features represented by unique symbols and separated into color groups. There are five (5) color plates which were used in the film-based reproduction process. The five (5) plates include vegetation (green), water (blue), public land survey lines and densely built-up areas (red), roads and buildings (black), contours and other elevation features (brown). Although, no longer used the color (purple) found on the historical topo maps represent feature changes.
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black plate
The color black is represented in a number of features including: boundaries, buildings, bridges, viaducts, tunnels, crossings, control data, monuments, dams, piers, break waters, foreshore and offshore features, mine symbols, roads, highways, trails, railroads, drive-in theatres, oil sumps, telephone lines, pipelines and wells.
Boundaries
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Civil township, town, district, precinct, barrio
Line weight .007”. Dash .17”. Space .033”. |
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County, parish, municipio, judicial division
Line weight .01”. Dash .25” and .07”. Space .033”. |
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Incorporated city, village, town, borough, or hamlet
Line weight .007”. Dash .08” and .04”. Space .02”. |
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Miscellaneous Boundary Data - Boundary in road
Boundary line weight .002”. |
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Miscellaneous Boundary Data - Cemetery
Space permitting omit cross and place name or label |
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Miscellaneous Boundary Data - Cemetery
If larger than .10” square add cross and omit label. If |
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Miscellaneous Boundary Data - Small cemetery-Topographic-Map-Quadrangle-Dillton
Omit cross if cemetery is .10” square or less. Add label if |
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National
Line weight .016”. Dash .25” and .07”. space .033”. |
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National or state reservation, park, or monument; very large city, county, or private park
Line weight .007”. Dash .25”. Space .10”. Dot .01”. |
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Small park, cemetery, etc
Line weight .003”. Dash .04”. Space .02”. |
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State or territory
Line weight .012”. Dash .25” and .07”. Space .033”. |
Bridges/Viaducts/Tunnels/Crossings
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Bridge: multiple track railroad
Same as single track except cross-tick length .05”. |
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Bridge over stream, road, railroad
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Bridge: road
Tick weight .003”. Wing-tick length .023”. Angle 45”. |
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Bridge: single track railroad
Tick weight .003”. Cross-tick length .035”. Wing-tick length .023”. Angle 45º. No crossties on bridges less than .40” in length and none closer than .20” to bridge ticks. |
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Drawbridge: railroad
Line weight .003”. Circle .045” overall. |
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Drawbridge: road
Line weight .003”. Circle .045” overall. |
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Ferry
Label placement for narrow water area. |
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Ferry
Line weight .003”. Dash .04”. Space .02”. Label. |
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Footbridge
Line weight .005”. Wing-tick weight .003”, length .023”. Angle 45º. |
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Ford: road
Line weight .003”. Dash .04”. Space .02”. Overall |
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Ford: road or trail
Label placement for narrow stream. |
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Ford: trail
Line weight .005”. Dash .04”. Space .02”. Label. |
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Tunnel: railroad
Line weight .003”. Overall width .017”. Dash .04”. Space .02”. Cross-tick length .017”. Wing-tick length .023”. Angle 45º. |
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Tunnel: road
Line weight .003”. Dash .04”. Space .02”. Wing-tick length .023”. Angle 45º. |
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Underpass, overpass
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Buildings
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Building placement
Center of symbol represents center of feature. If |
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Church
.025” x .025”. Cross length .04”. Cross bar .025”, |
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Church in congested areas
.02” x .02”. Cross length .033”. Cross bar .02”, .017” |
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Large buildings
Show solid to scale. Use for buildings greater than .05” |
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Large school or church
To scale if larger than .05” in longest axis. |
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Miscellaneous Structures - Cliff dwelling
Line weight .003”. Rectangle .017” x .03”. Base .05”. |
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Miscellaneous Structures - Covered reservoir
Hatch SW-NE with .002” lines spaced .02” center to |
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Miscellaneous Structures - Gaging station
Line weight .003”. Circle .05” overall. Divide in 4 equal |
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Miscellaneous Structures - Located or landmark object
Line weight .003”. Circle .04” overall. Dot .006”. |
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Miscellaneous Structures - Masonry swimming pool, reservoir, or fish hatchery
Line weight .003”. Blue tint fill for water, omit tint for |
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Miscellaneous Structures - Pumping station
Show to scale. Minimum size .02” x .02”. Label. |
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Miscellaneous Structures - Ruins
Line weight .003”. Dash .04”. Space .02”. Decrease |
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Miscellaneous Structures - Sewage disposal or filtration plant
Line weight .003”. |
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Miscellaneous Structures - Snowshed
Width same as crosstie. |
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Miscellaneous Structures - Tanks: oil, gas, water, etc
Circle .03” minimum. Label water tanks only. Show |
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Miscellaneous Structures - Windmill
Line weight .003”. Triangle .05” in height, angles 30º, |
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School
.025” x .025”. Flagpole length .04”, weight .003”. |
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School, college, etc
When more than one building, show flag on |
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School in congested areas
.02” x .02”. Flagpole length .033”, weight .003”. Flag |
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School or church placement
Flag or cross to clear other culture. |
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Small buildings
Show solid 02” x .02”. Use for buildings less than .05” |
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Small buildings in congested areas
Minimum .017” x .017”. |
Control Data-Monuments
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Bench mark coincident with found section corner
Show section corner on red plate. |
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Boundary monument with number and elevation
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Boundary monument without tablet, with or without geodetic position, elev. third order or better. Grant monument on red
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Boundary monument with tablet, with or without geodetic position, elev. third order or better. Grant monument on red
Line weight .003”. Sides .04”. Dot .006”. |
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Horizontal control station, checked spot elevation
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Horizontal control station coincident with section corner
Show triangle. Omit corner. Space .033”. |
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Horizontal control station, elevation third order or better
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Horizontal control station, third order or better, permanent mark
Line weight .003”. Sides of triangle .07”. Dot .006”. |
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Horizontal control station, vertical angle elevation
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Other control points. Object may or may not have geodetic position
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Reference monument
Line weight .003”. Sides .04”. Dot .006”. |
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Spot elevation
Line weight .002”. Length .06”. Angles 90º. |
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U.S. mineral or location monument
Base .06”. Height at center .04”. |
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Vertical control station marked with tablet, elev. third order or better
Line weight .003”. Length .08”. Angle 90º. |
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Vertical station, recoverable mark-no tablet, elev. third order or better
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Dams/Piers/Breakwaters etc.
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Breakwater, jetty, pier, wharf
Not exceeding .02” in width. Line weight .007”. Tint |
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Breakwater, pier, wharf, causeway
Exceeding .02” in width. Show to scale. Line weight .003”. If it carries road use proper road symbol. Break tint and shoreline. |
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Canal lock gate, double line stream
Line weight .007”. Tick to project .02” beyond canal. Angles 45º. Label. |
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Canal lock or sluice gate
Line weight .007”. Tick length .023”. Angles 45º. Point upstream. Label. |
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Covered pier or wharf
Break tint and shoreline. |
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Dam carrying road
Increase weight of road casing by .004”. Break tint. |
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Dam with lock
Weight of dam line .012”, lock .003”. Lock .075” x .033”. Angles 45º. Point upstream. Show to scale if larger than symbol. |
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Drydock
Line weight .003”. Tick weight .007”, length .023”. |
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Large masonry dam
Line weight .012”. If width of dam exceeds .02” show dam outline to scale and fill with radiating lines. Dam line weight .007”, other lines .003”. Drop contours at black dam line. |
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Seawall
Line weight .007”. Break shoreline. Label. |
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Small masonry dam
Line weight .012”. Line weight .007” for dam less than .20” in length. |
Foreshore-Offshore Features
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Area limits
Line weight .003”. Dash .10”. Space .02”. Label. |
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Danger curve
Line weight .002”. Dash .015”. Space .01”. Label. |
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Exposed wreck
Line weight .003”. Base .12” overall. Circle .025”. |
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Exposed wreckage or foul ground
Outline dots .008”. Space .017”. Label. |
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Foreshore flat
USGS 17. Label sand, gravel, mud, etc. If unknown |
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Group of rocks bare or awash
Line weight .003”. Length .05”. Angles 60º with outline dots .008”, spaced .017”. |
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Masts exposed on sunken wreck.
Line weight .003”. Length .08”. Cross ticks .033” and |
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Pile, dolphin, stump, or snag
Line weight .003”. Circle .033” overall. Label. Use |
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Rock bare or awash
Line weight .003”. Length .05”. Angles 60º. |
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Rock bare or awash dangerous to navigation
Length .05”. Angles 60º. Dots .008”. Space .017”. |
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Rock or coral reef
Limits as shown. Fill USGS 17. Label. |
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Shoal
Where depth curves do not show extent of shoal area |
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Small rock or coral reef
USGS 17. Label. |
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Sunken rock
Line weight .003”. Length .05”. Angle 90º. USGS 24. |
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Sunken wreck
Line weight .003”. Length .08”. Cross ticks .033” and |
Mine Symbols
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Gravel, sand, clay, or borrow pit
Line weight .003”. Length overall .08”. Arcs .04”. |
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Mine shaft
Line weight .003”. Square .04” x .04”. |
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Mine tunnel entrance or cave
Line weight .003”. Arm length .033”, shaft .067”. |
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Open pit mine or quarry
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Prospect
Line weight .003”. Length .067”. Angles 60º and |
Miscellaneous
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Boardwalk
Overall width to scale with minimum .02”. Line weight |
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Campground
Line weight .005”. Base .04”. Overall height .08”. Example links: Campground-Topographic-Map-Quadrangle-Aspen-Colorado-1964
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Coke ovens
Overall width .02”. Casing line weight .003”. Fill dash |
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Corral
Line weight .003”. Dash .04”. Space .02”. Label. |
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Drive-in theater
Outline area with Line weight .003”. Dash .04”. Space .02”.. Show structures. Label as Drive-in Theater. Screen line weight .007”. |
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Oil sump or sludge pit
Line weight .003” for outline if constructed of materials |
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Open oil reservoir
Outline weight .003”. Fill dots .006”, spaced .014” |
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Picnic area
Line weight .005”. Top length .05”. Leg length .025”. |
Other Culture Symbols
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Gas or oil pipeline aboveground
Line weight .005”. Label as Aboveground Pipeline. |
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Gas or oil pipeline underground
Line weight .005”. Dash .10”. Space .02”. Label as Pipeline. |
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Landmark lines: ski lift, incline railway, tramway, etc
Line weight .005”. Dash .10”. Space .02”. Label ski lift, incline railway, tramway, etc. Example links: Ski Lift-Topographic-Map-Quadrangle-Aspen-Colorado-1969
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Power transmission line
Line weight .003”. Dash .033”. Space .017”. Dot |
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Prominent wall
Show to scale. Show outline if width exceeds .017”. |
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Telephone line
Line weight .005”. Dash .10”. Space .02”. Label as Telephone. |
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Wall
Line weight .007”. Wall not exceeding .017”. Label as Wall. |
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Wells (excluding water)
Line weight .003”. Circle .033” overall. Label as Well. |
Railroads
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Miscellaneous - Carline
Line weight .005”. Tie weight .003”, length .04”, spaced .10” center to center. Not shown in urban areas or in streets or roads. |
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Miscellaneous - Dismantled railroad or carline
Line weight .005”. Dash .05”. Space .02”. Show if |
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Miscellaneous - Roundhouse and turntable
Line weight .003”. Show to scale. Minimum circle .06” overall. |
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Miscellaneous - Station
.02” x .04”. Use symbol when no siding, building, or other identifying feature. |
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Miscellaneous - Turntable
Line weight .003”. Show to scale. Minimum circle .06” overall. Cross line at 45º angle. |
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Narrow Gauge - Multiple Track
Line weight .005”. Tie weight .003”, length .02”, spaced .20” center to center of double tie. Double tie .02” overall width. |
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Narrow Gauge - Single Track
Line weight .005”. Tie weight .003”, length .02”, spaced .20” center to center. |
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U. S. Standard Gauge - Juxtaposition
Alternate ties, spaced .20” center to center. Minimum space between tracks .011”. Line weight for single tracks .005”, multiple tracks .003” |
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U. S. Standard Gauge - Multiple main line track
Overall width .017”. Line weight .003”. Tie length .052”, spaced .20” center to center. If more than two tracks label, with double crosstie at point of change. Double crosstie .017” overall width. |
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U. S. Standard Gauge - Railroad in street
Ties spaced .20” center to center. Label if narrow gauge. Tie weight .003”. |
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U. S. Standard Gauge - Sidings
Line weight .003”. Scribe to scale with minimum space between tracks .011”. Ties spaced .20” center to center, length .04” for single track. |
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U. S. Standard Gauge - Single track-Topographic-Map-Quadrangle-
Line weight .005”. Tie weight .003”, length .04”, spaced .20” center |
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U. S. Standard Gauge - Yards
Line weight .003”. Space between tracks .011”. Ties spaced .20” center to center, maximum length to touch 6 tracks.
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Roads, Highways and related features
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Class 1—Primary highway, hard surface, two or three lanes
Overall width to scale with minimum .02”. Line weight .003”. See symbol 513 for red fill. Label if 3 lanes. |
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Cloverleaf
Minimum overall width .10”. Show to scale if size exceeds symbol. |
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Dead end road
Use only when there may be a question as to whether road ends. |
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Dual highway, overall width 100’ or less
Overall width to scale with minimum .037”. Line weight .003” |
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Dual highway, overall width over 100’
Treat each side as individual road. Width of dividing strip (space) to scale. |
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Light duty, hard or improved
Overall width .02”. Line weight .003” |
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Primary highway, hard surface, four or more lanes
Class 1 road. Line weight to fit road casing. Overall width to scale with minimum .02”. Line weight .003” |
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Private road
Show if 500’ or more in length. Classify according to construction. Label only when necessary to clarify as to availability for public use. |
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Secondary highway, hard surface, four or more lanes.
Class 2 road. Line weight to fit road casing. Dash .12”. Space .12”. Overall width to scale with minimum .02”. Line weight .003”. |
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Secondary highway, hard surface, two or three lanes
Overall width to scale with minimum .02”. Line weight .003”. Line weight to fit road casing. Dash .12”. Space .12”. for red fill. Label if 3 lanes. |
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Streets in urban areas
Overall width to scale with minimum .02”. Line weight .003” |
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Toll road—Tollgate
Tick line weight .007”. Tick to project .02” beyond road casing. Label. |
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Traffic circle
Road width of circle that of widest road entering circle. Show to scale if size exceeds symbol. Minimum space in circle .04”. |
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Trails: important foot, bridle, pack, marked, and named
Line weight .005”. Dash .05”. Space .02”. Label when necessary to clarify. When used primarily for fourwheel-drive vehicles, label, “4WD”. |
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Under construction-Classification known (Class 1 and 2 only)
Overall width to scale with minimum .02”. Line weight .003”. Dash .10”. Space .02”. Red fill consistent with road classification. Label Under Construction |
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Unimproved dirt
Overall width .02”. Line weight .003”. Dash .05”. Space .02”. |
blue plate
Areas on topographic maps in blue represent water including aqueducts, canals, streams, lakes, ponds and other hydrographic features.
Canals/Aqueducts
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Aqueduct tunnel
Line weight .003”. Overall width .017”. Dash .04”. |
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Canal, flume, aqueduct
Line weight .005”. Width exceeding 50’ at 24 000. Example links: Canal-Topographic-Map-Quadrangle-Joliet-Illinois-1955
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Canal, flume, aqueduct, or perennial ditch
Line weight .005”. Width not exceeding 50’ at |
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Elevated aqueduct, conduit, flume
Tick weight .003”. Length .023”. Angle 45º. Label |
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Intermittent canal
Line weight .005”. Dash .17”. Space .12”. Dots .008”. |
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Intermittent ditch
Line weight .005”. Dash .17”. Space .12”. Dots .008”. |
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Navigable canal
Label NAVIGABLE CANAL when |
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Underground flume, penstock, aqueduct, or similar feature
Line weight .005”. Dash .05”. Space .02”. Label. |
Lakes/Ponds
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Dry lake or pond
Line weight .005”. Dash .07”. Space .02”. |
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Indefinite or unsurveyed shoreline
Line weight .005”. Dash .07”. Space .02”. Blue tint fill. |
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Intermittent lake or pond
Line weight .005”. Dash .07”. Space .02”. |
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Perennial lake or pond
Line weight .005”. Blue tint fill 13%, 120-line at 105º. |