Rebuilding Claiborne Avenue in New Orleans: georeferencing Sanborn maps and building configurable applications
Taking historical maps or aerial images and bringing them into a GIS is nothing new. This workflow was basically the start of GIS! But one massive change is the way that the results of georeferencing can be shared. Through StoryMaps, configurable applications, or just as layers; maps and the digitized data can be accessible in engaging applications by anyone with an internet connection.
This is a great workflow for students or researchers that are looking to compare the current built environment with historical snapshots, show change over time, or simply better understand a city’s history.
Check out the StoryMap that I put together here: N. Claiborne Avenue: Before the Expressway
Claiborne Avenue
I lived in New Orleans for a few years during graduate school and it is still one of my favorite cities in the world. The food, the history, the architecture, the culture; It all just screams N’awlins. The city oozes history, but some of that history still runs red from the scars of the past.
One such area, is along Claiborne Avenue in the Treme neighborhood. Cars and trucks roar across the elevated I-10 interstate and sunlight is completely blocked out. Chain link fences, massive concrete pillars, 6 lanes of traffic at street level; with fading storefronts and homes caught in the crossfire. At one time, this was the commercial heart of the Treme neighborhood, today, it’s a shadow of its former self.
One of the most powerful aspects of GIS and geography for me, is the ability to ‘rebuild’ the past. How did this commercial area change? Where were businesses? What did the oak tree neutral ground look like?
This same workflow could be conducted in virtually any city. To get started, students and researchers need access to historical photos and historical maps. Let’s start with the photos.
Historical Photos
Looking through the Historic New Orleans Collection (https://www.hnoc.org/), I found a few amazing photos of Claiborne Avenue that were taken in the late 1940’s. These brought the neighborhood to life in a powerful way. For my first step, I simply wanted to place these on a map in the locations that they were taken. Thankfully, each photo listed the street and intersection, so the direction/angle of the photos, as well as the locations were easy to determine. I then made a basic feature service where I added the photos as attachments and some fields for the name, source, etc. for the photos. This only took a few minutes.
Historical Maps
For this project, I wanted to visualize the morphology of this area prior to the construction of the I-10. What buildings and businesses had existed before the wrecking balls came through? What buildings were spared?
Sanborn maps provide amazingly detailed records of the urban environment. More amazingly, thousands of these maps are now digitized and available as high-resolution images that can be downloaded from the Library of Congress. Simply head over to the Sanborn Collection here: https://www.loc.gov/collections/sanborn-maps
After you download the images for your preferred location and time. You can then import these images into ArcGIS Pro to georeference them. There is also a great ArcGIS Learn Lesson built out for this workflow: https://learn.arcgis.com/en/projects/georeference-imagery-in-arcgis-pro/. This provides a nice way for learners new to the tools to walk through them and understand the process. They can then get started with their own data (Sanborn maps anyone?).
Building Footprints
After digitizing my Sanborn map, I wanted to compare current structures to those present in the historic Sanborn map. Rather than digitizing every building footprint, New Orleans has an Open Data Portal with all of their buildings: https://portal-nolagis.opendata.arcgis.com/maps/f8c4058a79ef4f3bbd56ebb790905566/explore
I started with this dataset and worked additively. With the Sanborn map open, I added in the historic buildings that were missing, and deleted the few that were new additions. This helped to speed up the process significantly.
After getting this feature class built out, I then published the dataset to my ArcGIS Online account.
Wrapping Up
The process that took the most amount of time was the digitizing and data clean up. Building the apps within the StoryMap application only took a few minutes. For next steps, I would love to have some photos of ‘today’ from these locations to build a ‘yesterday and today’ type application, along with the map.
With the availability of the Sanborn maps, configurable applications, Open Data sites, and historical images, any student or researcher could build out a similarly rich application for any locale (where data exists!). There is nothing like getting your hands a little dirty by going to an original source to create data. The ability to build something from scratch and then see the results in a beautiful, interactive application is possible for anybody.