OpenHistoricalMap

The OpenHistoricalMap domain name was purchased in 2009,{{cite web|title=Whois search results for openhistoricalmap.org|publisher=Amazon Registrar|location=Seattle|accessdate=September 6, 2023|url=https://registrar.amazon.com/whois?domain=openhistoricalmap.org}} and an initial fork of the OpenStreetMap website software was deployed there in 2013.{{cite conference|title=A Brief Technical History of Open Historical Map|first=Sanjay|last=Bhangar|date=April 2, 2022|publisher=OpenStreetMap U.S.|location=Tucson, Arizona|conference=State of the Map U.S.|url=https://openstreetmap.us/events/state-of-the-map-us/2022/brief-technical-history-of-openhistoricalmap/}}

{{Anchor|OpenHistoryMap}} In 2015, the similarly named OpenHistoryMap project was founded to promote sharing of archaeological and historical data according to an open access model. However, it has a peer review process,{{cite journal|title=Open History Map|first1=Silvia|last1=Bernardoni|first2=Marco|last2=Montanari|first3=Raffaele|last3=Trojanis|journal=Archaeologia e Calcolatori|publisher=Istituto di Scienze del Patrimonio Culturale|date=2017|volume=28|issue=2|pages=539–548|doi=10.19282/AC.28.2.2017.44}} which is distinct from the OpenHistoricalMap and OpenStreetMap projects' focus on volunteered geographic information.{{sfn|Litvine|El Gouj|Meyer|Starzec|2022|p=5}}

In 2016, OpenHistoricalMap suffered a hard disk drive failure but managed to recover most data from a backup that a contributor had made by chance. Since 2017, Oakland, California–based GreenInfo Network and Washington, D.C.–based Development Seed have developed and maintained the project's technical infrastructure.{{cite web|title=An Open Data Map of World History|publisher=GreenInfo Network|location=Oakland, California|accessdate=February 13, 2022|url=https://www.greeninfo.org/work/project/openhistoricalmap}}{{cite conference|title=Open Historical Map: Vector Tiles & Other Updates|first=Jeff|last=Meyer|conference=State of the Map U.S. 2019|date=September 8, 2019|page=4|accessdate=February 13, 2022|url=https://openstreetmap.us/events/state-of-the-map-us/2019/update-on-open-historical-map-using-the-osm-stack-live-with-vector-tiles/}} In 2018, longtime host Topomancy shut down and transferred ownership of the OpenHistoricalMap domain to the Wikiwar Heritage Council.{{cite mailing list|title=News regarding OpenHistoricalMap|first=Rob H.|last=Warren|mailing-list=historic|date=May 23, 2018|accessdate=April 14, 2022|url=https://lists.openstreetmap.org/pipermail/historic/2018-May/001150.html}}

In 2020, OpenHistoricalMap introduced a "time slider" that allows users to interactively filter map data by time period. This feature is credited with spurring the project's growth.{{sfn|Litvine|El Gouj|Meyer|Starzec|2022|p=5}} In May 2021, OpenHistoricalMap became a charter project of OpenStreetMap U.S., a nonprofit local chapter of the OpenStreetMap Foundation.

File:T21-2.jpg that has been georeferenced by the Regional Plan Association for mapping historic wetlands in OpenHistoricalMap.]]

OpenHistoricalMap allows anyone with a free account to contribute directly to the map through an editor such as the iD Web application or the JOSM desktop application. Contributors can georeference out-of-copyright maps and trace features from them.{{cite thesis|title=Koncept neokartografie ve studiu starých map|first=Daniel|last=Vrbík|type=PhD|publisher=Masaryk University|location=Brno|date=2018|page=55|url=https://is.muni.cz/th/ordot/metody_neokartografie_ve_studiu_starych_map.pdf#page=55|language=Czech}} They can contribute data individually or as part of guided mapathons.{{sfn|Litvine|El Gouj|Meyer|Starzec|2022|p=6}}

The software that powers the OpenHistoricalMap website is maintained on GitHub as a collection of open-source projects. Many of these projects, such as the iD editor, are forks of OpenStreetMap software projects that have been adapted to a data model with a time dimension.

File:Kuntisuyu and Antisuyu in 1500 in OpenHistoricalMap.png and Antisuyu regions and their provinces as of 1500.]]

The OpenHistoricalMap community has organized projects to map certain historical periods and themes in detail. Major contributions have included:

• Historical boundaries of U.S. states and counties, imported from the Atlas of Historical County Boundaries, a project of the William M. Scholl Center for American History and Culture at the Newberry Library{{Cite web |title=Home {{!}} Atlas of Historical County Boundaries Project |url=https://digital.newberry.org/ahcb/ |access-date=2023-03-03 |website=digital.newberry.org}}
• Historical boundaries within the Inca Empire{{cite web|title=Mapping the Tawantinsuyo in OpenHistoricalMap|first=Juan|last=Arellano|work=Cyberjuan|date=July 2, 2021|accessdate=April 14, 2022|url=https://cyberjuan.medium.com/mapping-the-tawantinsuyo-in-openhistoricalmap-c1c9ef156486|via=Medium}}
• The road network in France between 1820 and 1866, in collaboration with ANR-Communes and the Cambridge Group for the History of Population and Social Structure{{sfn|Litvine|El Gouj|Meyer|Starzec|2022}}
• The Jewish ghetto of Kolín{{cite journal|title=Transformation of the Jewish Space in Kolín, 1848–1921|first=Daniel|last=Baránek|journal=Judaica Bohemiae|publisher=Jewish Museum in Prague|location=Prague|volume=57|issue=1|date=2022|pages=67|url=https://www.ceeol.com/search/article-detail?id=1046590}}
• Trenches in the Battle of Vimy Ridge{{cite web|title=The Geometries of Vimy Ridge, 100 years ago|first=Robert|last=Warren|publisher=The Muninn Project|date=April 7, 2017|accessdate=February 18, 2023|url=https://blog.muninn-project.org/node/111}}

Individual mappers have also contributed data on the gentrification in the Cheonggyecheon and Dongdaemun areas of Seoul{{cite web|title=Cheonggyecheon, Dongdaemun Gentrification: Technical Notes|first1=E Roon|last1=Kang|first2=Wonyoung|last2=So|work=Seoul Libre Maps|date=August 29, 2017|url=https://medium.com/seoul-libre-maps/cheonggyecheon-dongdaemun-gentrification-technical-notes-375f69e5b2ad|via=Medium}} and former infrastructure related to Erie Canal and Harmony Mills in New York.{{cite conference|title=Life Cycle in OpenHistoricalMap|first=Richard|last=Welty|conference=State of the Map U.S. 2022|location=Tucson, Arizona|publisher=OpenStreetMap U.S.|date=April 1, 2022|url=https://openstreetmap.us/events/state-of-the-map-us/2022/openhistoricalmap-life-cycle/}} Mappers georeference old maps on platforms such as OldInsuranceMaps.net in order to complete the basemap.{{cite journal|title=Toward a Georeferencing Commons: A Crowdsourcing Case Study and the Creation of OldInsuranceMaps.net|first=Adam|last=Cox|work=Journal of Map & Geography Libraries|volume=19|issue=3|date=2023|page=160–184|doi=10.1080/15420353.2024.2326812|url=https://www.tandfonline.com/doi/full/10.1080/15420353.2024.2326812|url-access=subscription}}

OpenHistoricalMap focuses on historical objects but does not collect data on historical events per se.{{cite thesis|title=VGI protocol and Web service for historical data management|first=Rodrigo Monteiro|last=Mariano|type=Master's|publisher=National Institute for Space Research|location=São José dos Campos|date=March 11, 2019|pages=23–25|url=http://urlib.net/8JMKD3MGP3W34R/3SR2Q3H#page=49}}

OpenHistoricalMap has a data model largely identical to that of OpenStreetMap, including the consolidation of all data into a single layer. However, OpenHistoricalMap's addition of a time dimension makes the data more complex.{{cite report|title=Evolution of the OSM Data Model|first=Jochen|last=Topf|publisher=OpenStreetMap Foundation|location=Cambridge|date=15 August 2022|page=21|url=https://osmfoundation.org/wiki/File:2022-08-15-study-evolution-of-the-osm-data-model-by-Jochen-Topf_CC-BY-SA_4.0.pdf}} The tags for indicating a feature's start and end dates are much more important. There are multiple approaches to representing a real-world place or object that changes over time. It can be represented by multiple features in the database, each corresponding to different start and end dates. Alternatively, individual tags can be qualified by start and end dates, and more complex approaches involving relations have been proposed. Dates are formatted according to ISO 8601 or EDTF.

The OpenHistoricalMap project started from scratch with an empty database.{{sfn|Litvine|El Gouj|Meyer|Starzec|2022|p=5}} As of October 2021, OpenHistoricalMap's coverage was characterized as "very sparse" with few buildings mapped.{{cite conference|title=Software and Content Design of a Browser-based Mobile 4D VR Application to Explore Historical City Architecture|first1=Sander|last1=Muenster|first2=Jonas|last2=Bruschke|first3=Ferdinand|last3=Maiwald|first4=Constantin|last4=Kleiner|work=Proceedings of the 3rd Workshop on Structuring and Understanding of Multimedia heritAge Contents|publisher=Association for Computing Machinery|location=New York City|date=October 30, 2021|pages=13–22|doi=10.1145/3475720.3484442|isbn=9781450386685 |url=https://dl.acm.org/doi/abs/10.1145/3475720.3484442|url-access=subscription}} As of 2024, a triplestore representation of OpenHistoricalMap was comparable in size to an extract of OpenStreetMap data in Finland but had many more points than polygons, and of the polygons, many were similarly shaped.{{cite web|title=Efficient Spatial Joins for Large Sets of Geometric Objects|first1=Hannah|last1=Bast|author1-link=w:Hannah Bast|first2=Patrick|last2=Brosi|first3=Johannes|last3=Kalmbach|first4=Axel|last4=Lehmann|publisher=University of Freiburg Chair for Algorithms and Data Structures|location=Freiburg im Breisgau|date=June 9, 2024|url=https://ad-publications.informatik.uni-freiburg.de/SIGSPATIAL_spatialjoin_BBKL_2024.pdf}} OpenHistoricalMap's coverage includes multiple copies of an object as it changes over time.

On the main project website, a map consisting of vector tiles visualizes the historical data interactively in two styles, a functional Historical style and an artistic Woodblock style. A slider allows visitors to filter the map data to a point in time from 4001 BCE in the proleptic Gregorian calendar to the present day.{{cite web|title=Set new min date on timeslider|first=Dan|last=Rademacher|work=OpenHistoricalMap/issues|date=June 17, 2020|accessdate=February 13, 2022|via=GitHub|url=https://github.com/OpenHistoricalMap/issues/issues/28#issuecomment-645768215}} When a feature is selected, content from Wikipedia and Wikimedia Commons is displayed in a sidebar based on the tagged Wikipedia article title or Wikidata item identifier. A custom instance of the Nominatim search engine returns search results across time periods.

OpenHistoricalMap data is available for reuse in other projects. In addition to the REST API, a weekly database dump allows bulk downloads in Protocol Buffers–encoded OSM XML format. There is also an instance of the Overpass API for structured querying of the data across time periods. These tools are configured and deployed as part of the reusable osm-seed package.

Ecologists have used OpenHistoricalMap data to track the change of geological features over time such as the path of rivers.{{Cite book |last1=Travis |first1=Charles |url=https://books.google.com/books?id=DaZ9EAAAQBAJ&pg=PT594 |title=Routledge Handbook of the Digital Environmental Humanities |last2=Dixon |first2=Deborah P. |author-link2=Deborah Dixon |last3=Bergmann |first3=Luke |last4=Legg |first4=Robert |last5=Crampsie |first5=Arlene |date=September 12, 2022 |publisher=Taylor & Francis |isbn=978-1-000-63584-3 |page=594 |language=en}} Gramps Web uses an OpenHistoricalMap basemap to place genealogical data in a historical context.{{cite web|title=The new OpenHistoricalMap integration in Gramps Web|first=David|last=Straub|publisher=Grampshub|location=Munich|date=August 3, 2024|accessdate=August 24, 2024|url=https://www.grampshub.com/blog/en/2024/08/04/openhistoricalmap-in-gramps-web.html}}

Individual features within the OpenHistoricalMap database are licensed independently. The project prefers that new contributions be dedicated to the public domain through a CC0 dedication.{{cite web|title=Open Historical Map/OHM Basics|work=OpenStreetMap Wiki|date=September 3, 2021|url=https://wiki.openstreetmap.org/wiki/Special:PermanentLink/2194345#License}} However, a fraction of tagged elements have been contributed under other licenses, most commonly the Open Database License (used by OpenStreetMap) and Creative Commons Attribution-ShareAlike.{{cite web|title=license|work=OpenHistoricalMap Taginfo|accessdate=July 25, 2022|url=https://taginfo.openhistoricalmap.org/keys/license#values}}

The software that powers the OpenHistoricalMap website is available under the GNU General Public License.{{cite web|title=LICENSE at staging|work=OpenHistoricalMap/ohm-website|via=GitHub|accessdate=February 13, 2022|url=https://github.com/OpenHistoricalMap/ohm-website/blob/staging/LICENSE|archiveurl=https://web.archive.org/web/20220213105745/https://github.com/OpenHistoricalMap/ohm-website/blob/staging/LICENSE|archivedate=February 13, 2022|url-status=bot: unknown}}

• Historical geographic information system

{{reflist|30em}}

• {{cite conference|title=Setting a standard for open and collaborative data acquisition for historical cartography: digitizing the french État-major maps as a collaboration between the ANR COMMUNES and open historical maps|first1=Alexis|last1=Litvine|first2=Hanae|last2=El Gouj|first3=Jeff|last3=Meyer|first4=Arthur|last4=Starzec|first5=Thomas|last5=Thévenin|first6=Isabelle|last6=Séguy|first7=Christophe|last7=Mimeur|first8=Doriane|last8=Hare|first9=Raphaëlle|last9=Boissard|first10=Damien|last10=Roy|work=GeoHumanities|publisher=American Association of Geographers|location=Seattle|date=November 11, 2022|pages=1–7|doi=10.1145/3557919.3565811|url=https://dl.acm.org/doi/abs/10.1145/3557919.3565811}}

{{Commons category|OpenHistoricalMap}}

• {{Official website|https://www.openhistoricalmap.org/}}
• [https://wiki.openstreetmap.org/wiki/Open_Historical_Map OpenHistoricalMap] on the OpenStreetMap Wiki
• [https://lists.openstreetmap.org/listinfo/historic OpenStreetMap historic mailing list]
• {{GitHub|OpenHistoricalMap}}

{{OpenStreetMap}}

{{Volunteered geographic information}}

Category:History maps

Category:History websites

Category:Internet properties established in 2013

Category:OpenStreetMap

Category:Wikis about geography