This amazing, confusing-to-read, quilt was created from census data showing the nationality mix of the time – A glorious island of immigrants!
Here’s some of what the creator’s of the map had to say:
The census of 1890 obtained the nationality of the residents of each sanitary district by descent from the mother. The table in which this appears was made the basis of the nationality map. As a basis it will appear fair enough when it is considered that at the time of the census over seventy-six percent of the white population in the city had foreign-born mothers, and over forty per cent. were foreign-born themselves. So the latter certainly, and probably a majority of the thirty-six percent. of native-born of foreign mothers, would show the traits of their maternal nationality. All the nationalities given in the table are not plotted. The Scotch, English, Welsh, Scandinavian, and Canadians have not collected in colonies, but are scattered over the city. These, being in small numbers, and perhaps less foreign than the others, were disregarded.
Check out an awesome, cross-hatched 1890 density map, along with insightful commentary from Making Maps: Diy Cartography