Here is a link to a ward-by-ward break down of the illiteracy rate, with other demographic info on D.C.'s ~ 600,000 residents:
http://www.american.edu/ocl/volunteer/Community-Service-Center-Maps-and-Stats.cfm
Highest Illiteracy Rates By Ward
The below information breaks down the illiteracy rates by ward. For more information on wards go here
•Ward 7 50.4%
•Ward 8 48.9%
• Ward 5 48.2%
•Ward 1 43.6%
•Ward 4 42.2%
•Ward 6 37.3%
•Ward 2 20.8%
• Ward 3 8.2%
The 36% city-wide rate comes from another site that poped up on Google.