(Links below lead to Quick Facts for Delaware Counties: People, Business & Geography at U.S. Census Bureau.)
| Area | 7/1/2008 | 7/1/2007 | 7/1/2006 | 7/1/2005 | 7/1/2004 | 7/1/2003 | 7/1/2002 | 7/1/2001 | 7/1/2000 | Census 2000 |
| Delaware | 873,092 | 861,953 | 850,366 | 838,519 | 825,682 | 814,262 | 803,774 | 794,498 | 786,404 | 783,600 |
|---|---|---|---|---|---|---|---|---|---|---|
| Kent County | 155,415 | 151,705 | 147,520 | 143,206 | 138,319 | 134,173 | 131,274 | 128,812 | 127,110 | 126,697 |
| New Castle County | 529,641 | 526,408 | 523,194 | 519,824 | 516,103 | 512,370 | 508,773 | 505,415 | 501,859 | 500,265 |
| Sussex County | 188,036 | 183,840 | 179,652 | 175,489 | 171,260 | 167,719 | 163,727 | 160,271 | 157,435 | 156,638 |
Source: Population Division, U.S. Census Bureau