Address grids: coming soon to an OpenStreetMap near you

An A0-sized poster by Dan Jacobson (jidanni@OSM) ©2024 CC-BY-SA 4.0

  1. It is a sunny day in Highland Park, IL, USA. We pop in to the fire station on Burton Ave. to see what kind of maps they use (Map 1: northeast Highland Park).

  2. Now it's down the block to the Walgreens® pharmacy on Roger Williams Ave. where we purchase a Rand McNally™ street map (Map 2: NW HP, 3: SE HP).

    We ask the clerk, "Isn't there some map of Highland Park without those curious red lines (Map 1) and ticks (2, 3)?" The clerk sighs, "Yes: OpenStreetMap. You can't blame them though. In England all there is is odd and even addressing. New England too. Europe, etc. same story. Sad."

  3. Intrigued with Map 3, back in the lab we make our own version, Map 4 (and even discover that the two "0" axes could be expressed as a single folded axis, negative (west) addresses becoming positive (north) after the fold.) We also make Map 5 of the fire station and pharmacy.

    [Map 1: Highland Park IL USA Fire District map] [Map 2: NW corner of Highland Park IL USA] [Map 3: SE Highland Park, IL, USA] [Map 4: SE corner of Highland Park, IL, USA, our version] [Map 5: Roger Williams Ave. Highland Park, IL, USA]

  4. Looking closer at Map 2 we discover no less than three towns' grids, all at different angles. (Highland Park's oblique 1600-2200 hits Lake Forest's 100-600, and Deerfield / Bannockburn's 1000-1400.) Same story for hundreds of miles.

    There are even state-wide grids like in the Dakotas, determining every rural address and road name. Having a grasp of one's local grid is "life changing", and indeed you can leave your cellphone in the glove compartment, as you no longer need maps at all! (That address is just Y blocks (or tenths of miles, etc.) up and X blocks over from this address.)

  5. Enough! How to put address grids on OpenStreetMap? Oops. I mean how to tag address grids, enabling people to display them, in various ways, if they so wish? OK, let's see.

    At first glance at Map 5 (same as our poster's background map) Roger Williams Avenue maintains a constant grid value of let's say 725 north. So we might invent an additional OSM tag holding its grid value. Indeed in places like Utah streets' names often simply are their grid values: "300 West".

    But we also note there are many streets on our map that are not exactly aligned to the local address grid. So in fact maybe we should not get started tagging every individual street at all in the first place.

  6. E.g., many suburbs of Chicago share the same grid, so a single EPSG-like definition could list the point of origin (corner of State and Madison, 0, 0), numbers per mile for each direction (800, 800), which side is odd/even, etc.

  7. Digging deeper, we find address grids often have quite formal definitions, in city ordinances. Here they delineate those red 100 numbers per block lines seen in our images:

    There shall be and is hereby further established an Easterly Base from which shall be a straight line, the southerly limits of which shall be from a point in the center line of County Line Road projected, or the South Base Line hereinbefore established. This said point in the South Base Line shall be 3,200 feet east of the West Line of Section 31, Township 43 North, Range 13, East of the Third Principal Meridian. This Easterly Base Line shall extend northwesterly in a straight line to a point in the South Line of the Fort Sheridan Reservation projected 3,000 feet east of the West Line of Section 14, Township 43 North, Range 12, East of the Third Principal Meridian. Such Easterly Base Line shall further extend north on the same course. Lines shall thereupon be extended parallel to said South Base Line from east to west at intervals of 660 feet, and lines parallel to said Easterly Base Line shall be drawn from the south limits of the City to the north limits of the City at intervals of 660 feet, measured at right angles in each case to the base line.

  8. In that ordinance we notice references to the US Public Land Survey System, which along with Canada's Dominion Land Survey (DLS), underlies central and western North America's arrow-straight grid roads and checkerboard farm fields.

    So in fact any definition of Highland Park's address grid should be anchored on the PLSS. Same with that "Corner of State and Madison" casually mentioned earlier. It would not tied to WGS84, but instead tied to the PLSS, which then ties to WGS84.

    But how about Highland Park's diagonal southeast to northwest grid lines? Well we'll need to take the azimuth of their baseline and establish a transverse Mercator grid...

    Or just with our mouse copy the positions of a few ground truth "ground control points" (GCPs),

    -gcp -575 692 -87.784315 42.164964 # Highland Park Fire station #32, 692 Burton Ave
-gcp -632 720 -87.786460 42.165401 # Walgreens Pharmacy store #5428, 632 Roger Williams Ave
-gcp ...

    All we needed were three to create the red grid lines you see on Maps 4 and 5.

  9. Conclusion: let's not wait years and years for Google® to maybe create some standard. Let's do it!

    Notes: 1) San Francisco CA has a street grid, but not an address grid. 2) openstreetmap.org/wiki/Addresses#Interpolation are address ranges, not address grids.

    Project home: https://www.jidanni.org/geo/house_numbering/grids/.