"200 years of the Census in Yorkshire"(pdf). National Statistics. 2001. Diakses tanggal 2008-07-15. Note that the area of Yorkshire increases slightly from 3.669.510 ekar (14.850 km2) in 1831 to 3.883.979 ekar (15.718 km2) in 1901 and then reduces to 2.941.247 ekar (11.903 km2) in 1991, so that these three figures relate to different areas.