Population measures provide insight on how communities are changing in size and composition. The age distribution of a population affects a community's character and the services that it requires. For example, an area with a large concentration of youth will have different service needs now and, in the future, than an area with a large elderly population.

From 2000 to 2017-21 in Lancaster County, there was more growth in older age brackets among both males and females. Among females, there was a 49% increase in the population aged 85 and older and a 51% increase in the population ages 60 to 84. Among males, the greatest increases were in the age brackets of 85 or older (85%) and 60 to 84 (70%). While the population 85 and older increased more significantly among males than females, there were more 85 and older women than men (9,300 and 5,100 respectively). Both genders had much smaller increases in the age brackets of 20-39 (10% for females, 11% for males).

The age brackets of 40-59 and 60-84 increased for both males and females in Lancaster County and neighboring counties. Pennsylvania and the U.S. were generally similar to Lancaster County, with some exceptions. For example, the population of females aged 60-84 increased 26% statewide, compared to 51% at the county level, which is closer to the nation's 54% increase over the same time period.

Individuals age into and out of these groups, and this indicator should not be interpreted as a measure of groups moving to or away from the region. The multiyear figures are from the Census Bureau's American Community Survey. The bureau combined 5 years of responses to the survey to provide estimates for smaller geographic areas and increase the precision of its estimates. However, because the information came from a survey, the samples responding to the survey were not always large enough to produce reliable results, especially in small geographic areas. CGR has noted on data tables the estimates with relatively large margins of error. Estimates with three asterisks have the largest margins, plus or minus 50% or more of the estimate. Two asterisks mean plus or minus 35%-50%, and one asterisk means plus or minus 20%-35%. For all estimates, the confidence level is 90%, meaning there is 90% probability the true value (if the whole population were surveyed) would be within the margin of error (or confidence interval). The survey provides data on characteristics of the population that used to be collected only during the decennial census. Data for this indicator are released annually in December.