This article is full of carefully constructed lies.
As an example, Prince William County has more white people in it now than ever before. The white population grew by 20% between 2000 and 2010.
Why does the author say that the white population declined by 23%? Because it suits his narrative - and likewise AF's narrative - of replacement.
"Grew" and "declined" relative to what, respectively? Without telling us this, there is no way to judge the merit of your criticism.
The white population might have grown by 20% relative to the previously existing white population, while still having declined by 23% relative the overall population.
I don't know if that is what happened or if, as you assert, the author is playing a shell-game with statistics.
But if it is the latter case, what you have said here is not by itself sufficient to demonstrate it.
I'll be curious to see if somebody actually parses the numbers to find out.
ETA - I took it upon myself to look the numbers up: turns out you are absolutely right.
Overall population increased from 280 to 400 thousand, but the percentage of that population that was white decreased.
Looks like all the numbers check out. It is important to note that by "white," the author of the OP article is apparently referring to the "White / Not Hispanic or Latino" classification used by the U.S. Census Bureau. According to the U.S. Census Bureau, "the concept of race is separate from the concept of Hispanic origin" and "[White / Not Hispanic or Latino] are individuals who responded 'No, not Spanish/Hispanic/Latino' and who reported 'White' as their only entry in the race question." Note also that, in what follows, "white" means "white alone" (i.e., it accounts for those who reported "White" as their only entry in the race question). Thus, the "White / Not Hispanic or Latino" population is a subset of the merely "white" population.
According to the U.S. Census Bureau
[1], the overall population of Prince William County, Virginia in 2000 was 280,813 and the white population was 193,574 (with the "White / Not Hispanic or Latino" population recorded as 181,756). Thus, the white population composed 69% [193,574 / 280,813] of the overall population in 2000 (with the "White / Not Hispanic or Latino" population composing 65% [181,756 / 280,813] of the overall population).
According to the U.S. Census Bureau
[2], the overall population of Prince William County, Virginia in 2010 was 402,002 and the white population was 232,401 (with the "White / Not Hispanic or Latino" population recorded at 195,656). Thus, the white population composed 58% [232,401 / 402,002] of the overall population in 2010 (with the "White / Not Hispanic or Latino" population composing 49% [195,656 / 402,002] of the overall population).
Based on these figures, from 2000 to 2010 there was (1) a decline of 11% [69% - 58%] in the white population relative to the overall population (with a decline of 16% [65% - 49%] in the "White / Not Hispanic or Latino" population), and (2) an increase of 20% [(232,401 - 193,574) / 193,574] in the white population relative to the previously existing white population (with an increase of 8% [(195,656 - 181,756) / 181,756] in the "White / Not Hispanic or Latino" population relative to the previously existing "White / Not Hispanic or Latino" population). This verifies and confirms TheCount's claim that "[t]he white population grew by 20% between 2000 and 2010."
The author claimed that "Prince William County, Virginia [...] experienced a 23 percent decline in the white population since 2000 [...]." Assuming, as seems obvious, that this claim was made about the white population relative to the overall population (and keeping in mind the note I mentioned in my opening paragraph), we should expect what the author refers to as the "white population" at the end of the claimed decline to be 42% [65% - 23%] of the overall population. This perfectly agrees with the U.S. Census Bureau's own estimate
[3] that, as of July 1st, 2018, the "White / Not Hispanic or Latino" population composed 42% of the overall population. (The U.S. Census Bureau also estimates
[3] that, as of July 1st, 2018, the overall population of Prince William County, Virginia was 468,011, and that the white population, as distinct from the "White / Not Hispanic or Latino" population, was 63% relative to the overall population.)
[1] PDF:
U.S. Census Bureau, 2000 Census of Population and Housing, Summary Population and Housing Characteristics, PHC-1-48, Virginia, U.S. Government Printing Office, Washington, DC, 2002
[2] PDF:
U.S. Census Bureau, 2010 Census of Population and Housing, Summary Population and Housing Characteristics, CPH-1-48, Virginia, U.S. Government Printing Office, Washington, DC, 2012
[3] https://www.census.gov/quickfacts/princewilliamcountyvirginia