Counts and percentages answer different questions
Absolute population change is ending population minus starting population. If a place rises from 100,000 to 110,000 residents, it adds 10,000 residents. Percentage growth is 100 × (110,000 / 100,000 − 1), or 10%. This is an illustrative calculation, not a claim about a named place.
A larger place can add more residents while growing more slowly in percentage terms. A small starting population can produce a large percentage change from a modest numerical increase. Rankings should therefore distinguish absolute increase from percentage growth and expose any minimum-population threshold.
Elapsed time matters
A five-year increase of 10% is not 10% annual growth. Annualized growth is 100 × ((ending / starting)1 / elapsed years − 1). For the illustrative totals above over five years, the rate is about 1.92% per year. This is the constant rate that connects the endpoints; actual annual changes can differ.
July 1 to July 1 comparisons have an explicit whole-year interval. A census count on April 1 and an annual estimate on July 1 have different reference dates. Do not call an April-to-July multiyear interval an exact five years, and do not mix a census count with an estimates base without explaining which starting observation is used.
Percentage points describe changes in a share
A population share is a numerator divided by a matching total, multiplied by 100. If a group's share rises from 20% to 25%, the increase is five percentage points. Relative to the original 20% share, that is a 25% proportional increase. Both calculations can be valid, but they have different units and meanings.
Use a common population universe and source definition for numerator and denominator. Overlapping race and Hispanic-origin categories cannot be summed as if they were mutually exclusive groups. Recompute a combined-region share from summed counts rather than averaging county percentages.
Invalid denominators and rounding
Suppress percentage growth when the starting total is zero or invalid. Annualized growth requires positive populations and a positive elapsed interval. Missing observations must not be treated as zero. Calculate with unrounded counts and round only the display; abbreviated labels such as “1.1M” are unsuitable as calculation inputs.
The growth calculator applies these rules to your values. The comparison tool uses compatible official observations. Read the site calculation methods and Census population-estimates definitions for source-specific terms and rate denominators.