Excerpt of article by Emiliano Gomez, March 27, 2019:

"In 2010, parts of three New Haven neighborhoods — Fair Haven, Newhallville and Edgewood — were designated by the Census Bureau as especially “hard to count” tracts due to low mail-return rates of census forms — less than 60 percent.

Such neighborhoods are mostly composed of groups the Census Bureau has designated “hard to count.”

All three of these neighborhoods, for example, are home to overwhelmingly non-white communities, which have lower response rates. DataHaven research from 2016 estimates that more than 80 percent of the residents in the three areas are people of color. The section of Newhallville listed as “hard to count” is 99 percent non-white."

Link:
https://yaledailynews.com/blog/2019/03/27/new-haven-census-coordinators-plan-efforts/