At Worlds Revealed, the Library of Congress’s map blog, Tim St. Onge looks at, and provides the background on, a series of six maps prepared by Frederick E. Pierce for a report on living conditions in New York’s tenement housing in 1895, including a stunningly bizarre map of ethnic groups living in the city.

Pierce’s map of nationalities, however, is a more memorable, if confounding, centerpiece. Aiming to convey diversity among immigrant communities in New York, the map depicts the proportion of major “nationalities” in each sanitary district of the city. The result is a dizzying array of zigzag stripes and scattered points. As Pierce writes in his explanatory notes accompanying the Harper’s Weekly publication, the original map was produced in color and adapted to black and white for publication, but the reproduction “is almost as effective and quite as illustrative as the original.” Despite Pierce’s confidence, perhaps the average reader could be forgiven if they find the map to be more difficult to parse. In fact, the map seems to resemble more closely the dazzle camouflage, a design aimed at confusing the observer, used on British and American warships in the first half of the twentieth century.

The Displacement Alert Project Map is a tool built by the Association for Neighborhood and Housing Development that maps, building by building, the risk of gentrification in New York City—i.e., where the rent is about to get too damn high. Intended for use by housing advocates, tenant organizers, community groups and others, the map calculates the risk of displacement—being pushed out of affordable housing—based on several factors. “Access to this data equips communities with information necessary to fight back against the displacement of residents who are being priced out and pushed out of their neighborhoods, to stop the harassment of tenants by bad landlords, and to prevent the expiration and loss and affordable housing units.” [Gothamist/Maps Mania]

It's been a while since I've published a map so here's 2015 house prices by postcode across Britain pic.twitter.com/p5AexvYokS

— Neal Hudson (@resi_analyst) April 14, 2016

[Maps on the Web]

Data available through the Consumer Data Research Centre’s map interface include age of residential properties (modal age and percent built after 1945) and top method of travel to work (screenshot above) for the U.K.