In 2000, the U.S. Census Bureau mistakenly listed the prison population in one census tract instead of the correct census tract. Oregon Secretary of State Bill Bradbury used the incorrect data when re-drawing the state's legislative districts as is done after each census.
The U.S. Census Bureau made an error by including the prison population in the wrong census tract in 2000, and this mistake was used by Oregon Secretary of State Bill Bradbury to redraw the state's legislative districts following the census.