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Supercharging

Historical Society Projects

with Open Source data & OHM

Jeff Meyer (OpenHistoricalMap)

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Why OpenHistoricalMap (OHM) for Historical Societies?

Free�
Creates & supports group activities & collaboration�
Easy to show off your work & progress�
Consolidates multiple types of digital data�
Can tell a focused story, with context�
Gives your group’s work credit for others to see

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The most important things to know about OHM

Anyone can make a map�
You don’t have to start from scratch to make a map

Old Maps + Open [GIS, Pictures, News] Data + OHM = Magic
There’s no need to recreate the wheel - the info is already there�

We have *lots* of support

Online documentation & how to’s for OpenStreetMap, which work for OHM
People online every day to get community-based assistance�

Almost more of digital scrapbooking than purely mapping

A lot of the work is more curation than creation (which is a good thing!)

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Quick background: OHM = OpenStreetMap + mods

Wait… what’s OpenStreetMap (OSM)?�
User-created map with global coverage

7+ million mappers worldwide�

Used by leading tech companies

Amazon, Microsoft, Facebook, TomTom, etc.
If you know, you’ll see OSM maps everywhere�

Users can get started immediately

Just create an account & you are off to the races

Seattle’s historic neighborhood Ballard in OSM

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So… how is OHM different from OSM?

OHM has a LOT less mapped

This is an opportunity for historical societies!�

OHM wants & loves OLD STUFF�
Timeslider to show change over time�
“Inspector” enhancements

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OHM plays well with your prior work!

Adds images & related info links�
Contextual background (e.g. old streets & buildings) for your existing info & stories�
Easily add & improve information on an ongoing, incremental basis

Add images

Links to prior work & websites

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OHM helps build on your prior work!

Every old picture becomes a basis for building a better map, to tell a richer local story

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Helps tie your work to others’ efforts

See what was going on in related cities at the same time, just by sliding the map around�
Regionally, nationally, etc.�
Adds historical context

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Tasking Manager enables team-based projects

Provides scope, direction, and instructions for group projects�
Keeps mappers from duplicating effort, stepping on each others’ edits�
Helps coordinate management & quality control aka validation�
Provides tracking statistics

https://tasks.openhistoricalmap.org/

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Potential projects

Mapping old city directories
Mapping old newspaper ads & photos
Thematic mapping:

Types of old buildings: schools, saloons, churches, fellowship halls
Old transport: Old rail and trolley lines; cobblestone streets, waterways
Areas lost to highways, development, fires, etc.

Micromapping:

Old intersections, ethnic neighborhoods, park histories

Tools exist to help with all of these types of mapping… just ask!

Data exists to help with all of these

And… even old maps can be used to extract this data : )��AI is here to help…

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Sanborn Maps: great example of OHM mapmaking ease

Great way to get started quickly�
Easy integration with OldInsuranceMaps.net �
Tons of information to extract�
Edit maps right away in your browser

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Next Steps!

Visit openhistoricalmap.org and check out the experience

US state borders from 1787 - today
Early Boston (1804), Manhattan & Brooklyn (1600), and Seattle (1840) waterline changes �

Check out our [[[quick start guide & tools]]]�
Reach out! jeff@gwhat.org

OHM representatives are always available to present to your team
Free brainstorming / digital storytelling consulting ; )
Ask for the world & whatever will make your life easier
Don’t hesitate to tell us what we need to do better

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Backup slides

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Detail slides

Map data – what is it? where to get it?

Open data – government portals
Maps & warping

Editing maps

Tracing pro tips
Filtering is your friend

Tagging

Critical tags
Yes, sourcing is critical

Missing features:

“Tours” / “Focus Maps” – creating, discovering, viewing
Better picture support – linking, representing
Map “underlays” – controlling, enabling
Crediting / promoting historical societies
City directory view
Newspaper integration

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What is map “data” and where do I get what I need?

Map data is just the information a web map uses to draw a map – lines, shapes, points – all connected to points on the earth.�
Luckily, many people have already created a ton of map data they share freely. This is called “Open Data.”�
You can draw/create the data on your own – it’s not that hard! This is often called “tracing” or “vectorizing” old maps.�
Or, you can use both of these methods! [my personal favorite]

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How far can you go with open data & history?

Turns out… pretty far!�
Example: Staten Island (1800-)

Source: NYC Open Data
Data: land cover, roads, building footprints, paths, etc.�

Key need: start_date info & tags

May need to make some reasonable assumptions about dates, add that to the data & fine tune with better sourcing

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Where to find Open Data?

Look at your locality in OHM… there’s probably a lot of open data already there�
Local government open data portal
State agencies
Local universities�
File formats: shapefile, geojson�
You just download these files and upload to your editor… and then, the curation and magic begins

Replace with agency appropriate for historical society

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Where to find maps to edit?

Pretty much anywhere online�
If you can download the map image, you can warp it at MapWarper.net�
If the map has an IIIF link, you can warp it at Allmaps.org �
Some sites have their own warpers & xyz or direct links to open & edit in OHM

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Georeferenced Map Sources

Site	Geo Coverage	xyz URL	1-click to OHM
David Rumsey Map Collection	Global	✅	⃞	follow up with Petr
MapWarper.net	You upload	✅	⃞	note sent to Tim
Allmaps.org	Global	✅	⃞	follow up with Bert
OldInsuranceMaps.net	US Sanborns	✅	✅
Any ArcGIS server layer with tiles enabled	server- specific	depends…	⃞

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Lots of GREAT Open Data for Mapping Old Richmond

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Lots of GREAT Open Data for Mapping Old Richmond

https://richmond-geo-hub-cor.hub.arcgis.com/search?collection=Dataset

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Using Old Maps: Sources and formats xyz, wmts, IIIF

Key: georectification

Sources:

Map libraries
Rumsey
Allmaps
LoC
Wikimedia Commons
Mapwarper
Many others…. sometimes you have to be clever

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Common Old Map Series in the US

Sanborn
Baist

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Patterns of City Growth in the US (esp. the West!)

Claim (dubious)
Plat
Plan
Build
Annex
Optional:

Fire
Rename Streets

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Tags change over time

What’s highway=secondary in 1800?

Aren’t they all highway=bridleway in 1800?

Using TagInfo!

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Key Old Maps of Richmond

1737 - Mayo’s Map��1797 - Map of Part of Richmond

1848 - Morgan Map

1862 - Geographical Sketch of The City of Richmond, Virginia, with Surrounding encampments, 1862

1858/64 Map of the City of Richmond, Virginia. From a Survey by I.H. Adams, Assist. U.S. Coast Survey, 1858, with additions from Smith's Map of Henrico County, 1853. Prepared at the U.S. Coast Survey Office, A.D. Bache Supt. 1864�

1877 - Beers Atlas - https://www.loc.gov/item/2005630891/ - IIIF

1886 - Sanborn

1889 - Baist - https://digital.library.vcu.edu/islandora/object/vcu%3Abai & INTERACTIVE!! (thank you, Internet Archive)

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Using Allmaps.org to set up tiles for an old atlas:

1877 Beers Illustrated Atlas of the city of Richmond

Citywide Atlas – 21 sheets and 5 detailed scenes

In between 1867 and 1892 city expansions

Predates 1886 Sanborn and 1889 Baist atlases

Available on Library of Congress website

Library of Congress supports an imagery standard called IIIF

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Allmaps.org and IIIF georeferencing… it’s *very* cool

Go to editor.allmaps.org/#

and paste the IIIF link for the 1877 Beers Atlas (https://www.loc.gov/item/2005630891/manifest.json) that you copied from the Library of Congress site

and click

…

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… and it automagically imports *the whole album*!

Voilà! Amazing!!

Even *more* amazing… if anyone has ever georeferenced any of these maps already on allmaps (or if allmaps has been able to import the georectification info)… allmaps will automatically provide that for your use.

Let’s see… I’ll click on the overview map & then click “Georeference”

1

2

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Initial Georeference page on allmaps.org

Alas… it looks like I’m the first to do this.

No worries, it’s an easy process. : )

And… once I’ve done it, everyone will be able to reuse what I’ve done.

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Georeferencing at work…

Best practices for georeferencing is a presentation of its own, �so we won’t go too deep here.

But… the first thing I notice is that north is *not* straight up on this map…

My first pass: scattered points around the city

This will align the map,�making it easier to fine-�tune with more points…�but… there are limits�with large area maps…

To finish, click “Results”

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Georeferencing **RESULTS**

Best practices for georeferencing is a presentation of its own, so we won’t go too deep here.

Add to JOSM

Use this map to get a sense of which streets are around at this point… combining with RichmondVAGIS info.

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Non-precision mapping with non-precision georeferencing…

but… not bad, either…

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Removing modern roads not on the old maps

Don’t delete ‘em…

tag ‘em (don’t change the dates until last)

let your date filters remove them….

Once you get the hang… grab a bunch at once (Shift-click)

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Even on relatively well-georeferenced maps, things can be “off”

… and updating georeferencing to be perfect can be tedious, frustrating, and sometimes… impossible! (yes!)

The red shape signifies the modern location of this block, and likely the historical location of the block, too.

How to resolve?

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Trace [old] and adjust [to the new]!

Create a new layer… so the other stuff isn’t in your way

Trace the old buildings there…building tool, rectify, line are all your friends in JOSM….

Move the whole thing to align with the modern (correct?) block shape

Copy in place to your editing layer.

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Historical map accuracy… it ain’t what it used to be

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Key Old Maps of Virginia - Roads, etc.

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Find a better detail of this map…

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When to use which georeferencer / warper?

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Problems with Georectifying Large Areas (more than a few blocks…)

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MapReduce! (whoops…) – GCP Reduce!

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Adding images!

Internet Archive is your friend

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Adding other sources

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Mapping old roads over large areas…

e.g., Map Showing the Location of Battlefields of Virginia (1892, Poole Brothers, Engravers, Chicago)�(IIIF)

Best practices:

Don’t

Too much spatial variation
Find smaller maps

Find someone who’s already done it
and/or… try to match as closely as possible to existing roads where you have data and then reuse that

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Mapping old roads over large areas…

e.g., 1864 Map of the vicinity of Richmond and part of the Peninsula, (IIIF) (allmaps.org) (xyzTiles)

Best practices:

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Mapping old roads over large areas…

e.g., 1861 Colton’s new topo map of eastern NC & VA (IIIF)

Best practices:

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Mapping old roads over large areas…

e.g., 1861 Colton’s new topo map of eastern NC & VA (IIIF)

Best practices:

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Using modern references can make up for historical spatial inconsistencies...

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You may be tempted to fix this with more GCPs in your georeferencer… avoid the temptation to pull that thread…

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1930s AAA �Road Map

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Working with natural features

Names… they weren’t there forever…

Human terraforming�particularly in the watershed and seawalls, ports, but hills, too

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Thematic Mapping

Recreating old maps - e.g. pick 1 and transcribe it completely!

Micromapping places - Shockhoe Hill, streets, neighborhoods, parks

Topical - cemeteries, formerly enslaved neighborhoods, specific buildings, intersections, neighborhood names, park history, red zones, trolly routes, cobblestone roads and alleys

Starting small - just adding points

Old watersheds -

Old fuzzy placenames -

Rails / roads

Key public buildings / amenities - schools, churches, hotels, pubs