Region 1: Connecticut, Vermont, Massachusetts, Maine, New Hampshire, Rhode Island
Region 2: New York, New Jersey
Region 3: Pennsylvania, Virginia, West Virginia, Maryland, Delaware, Washington, D.C.
Region 4: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Puerto Rico, U.S. Virgin Islands
Region 5: Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin
Region 6: Arkansas, Louisiana, New Mexico, Oklahoma, Texas
Region 7: Kansas, Iowa, Missouri, Nebraska
Region 8: Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming
Region 9: California, Arizona, Hawaii, Nevada
Region 10: Washington, Alaska, Idaho, Oregon
Source: http://portal.hud.gov/hudportal/HUD?src=/localoffices/regions
also: https://www.huduser.gov/portal/regions/Regional.html