Historically, foreign-born Americans and their descendants have been a key driver of population growth across the U.S. This metric serves as an indicator of community diversity and regional growth, highlighting where specialized services like language and resettlement services may be required. However, increased federal immigration enforcement has introduced new complexities: high-density immigrant communities may face increased scrutiny, and a subsequent decline in national immigration rates may trigger population stagnation or decline.

In 2020-24, 6% of Lancaster County's population was foreign-born, up one percentage point from 2010-14. The percentage of foreign-born people in Lancaster County was slightly lower than Pennsylvania, at 8%, and lower than the nation, at 14%.

Among neighboring counties, there were slightly smaller shares foreign-born populations in Lebanon and York (both 4%) and larger shares foreign-born populations in Chester, Berks, and Dauphin (all at 10%) and Cumberland (8%). The City of Lancaster had the largest share at 13%, an increase from 9% in 2010-14. Among comparison counties, Dauphin County had the largest increase, up 4 points 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.