Population measures provide insight on how communities are changing in size and composition. The racial and ethnic makeup of a community can offer insight into its levels of diversity, which also may reflect particular challenges and opportunities.

Overall, the U.S. population has become more diverse as a result of long-term immigration and natural demographic forces. While immigration at the national level has slowed due to recent policy shifts, several decades of steady immigration both increased and diversified the nation's population. Furthermore, racial and ethnic minority populations are expanding through higher birth-to-death ratios, while the aging non-Hispanic White demographic is experiencing a contraction as deaths outpace births.

From 2010-14 to 2020-24, Lancaster County's Hispanic population increased the most, at 31%, followed by the Asian population at 27%. Its African American population increased by 3% and its White population declined by 3%. Despite these shifts, the White population still makes up a large majority, with about 455,000 residents.

The growth in Lancaster County's Hispanic population from 2020-24 outpaced the nation but was lower than the state. Lancaster had the smallest growth rate among Hispanics compared to surrounding counties but was closest to Chester at 33%. The growth in Lancaster County's African American population was higher than Dauphin (3%) and lower than York (21%), Lebanon (24%), and Cumberland (49%). Chester and Berks were the only counties to experience a decrease in its African American population.

Rate is percentage change from 2010-14. 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.

The Census Bureau asks people to identify their race (white, African American, etc.) separate from their ethnicity (Hispanic or non-Hispanic). So the totals for these categories cannot be added together, as people show up in both a racial and ethnic group.