Redlining gets its name from the red areas on maps created for mortgage companies. The red areas note “dangerous” neighborhoods where it was considered risky and unprofitable to lend money for houses, regardless of the applicants’ income. Since cities were (and frequently are) so segregated, this meant that many blacks and Latinos had a very difficult time getting loans. While racial discrimination in housing lending is officially illegal, low home ownership amongst these groups persists to this day. 

This map is from Philadelphia and was published in 1934. Click through for more information.