What social and cultural changes occurred when the foreign-born percentage reached its 20th-century low?
Executive summary
When the foreign‑born share of the U.S. population hit its 20th‑century low of about 4.7% in 1970, the country was undergoing rapid social and cultural shifts tied to declining immigration, rising suburbanization, and changing public attitudes toward race, religion and national identity (Congress Research Service notes the low of 4.7% in 1970) [1]. Historical and recent scholarship ties lower immigrant shares to slower population growth, shifts in religious composition and political debates that later drove the 1965 policy changes that reopened immigration pathways (Wikipedia overview of immigration epochs; CRS demographic data) [2] [1].
1. Postwar lull: demography reshaped daily life
The foreign‑born share hitting its low meant fewer recent immigrants in neighborhoods, schools and workplaces; that demographic lull contributed to slower cultural refreshment from new languages, foods and religious institutions in many communities and set the stage for the suburban, more homogenous social landscape of the era (the foreign‑born proportion reached a low of 4.7% in 1970 per Congress Research Service) [1]. Available sources do not detail neighborhood‑level cultural markers in 1970, but the CRS data make clear the national numerical trough [1].
2. Religion and institutional support shifted
Large immigrant groups had long bolstered institutions such as Catholic parishes and ethnic mutual‑aid societies; as immigration waned, those institutions saw changing roles and slower influxes of congregants from abroad, reshaping their outreach and political influence (Wikipedia’s account links Catholic migration and immigrant support networks to earlier waves) [2]. Sources do not provide precise measures of institutional membership decline tied to the 1970 low; they establish only the historical connection between immigration and institutional development [2].
3. Politics: a lull that preceded reform and backlash
Low immigrant shares fed narratives that immigration was a “problem solved” in mid‑century politics and helped create bipartisan space for the 1965 Immigration and Nationality Act changes that followed—an act widely cited as a turning point that later produced large post‑1965 increases in immigration (Wikipedia frames U.S. history in immigration “epochs,” with policy shifts informing later rises) [2]. Sources do not claim a single causal chain but show that mid‑century demographics and politics were linked to later legislative change [2].
4. Fertility, labor and economic composition
A smaller foreign‑born population altered the age and fertility composition of the nation; several agencies and analysts later tied lower net immigration to changes in fertility and workforce projections, because immigrant women historically contributed higher fertility rates and younger cohorts to the U.S. population (CBO notes that changes in net immigration reduce the number of foreign‑born women of childbearing age and lower projected fertility) [3]. The CBO frames these as projection mechanics rather than direct social judgments [3].
5. Public attitudes and media framing hardened
The mid‑century low coincided with rising public debates about race, assimilation and national identity; contemporary and later accounts show that anxieties about “ethnic difference” in earlier decades produced restrictive laws and persistent cultural anxieties that shaped mid‑century discourse (Wikipedia notes animosity toward certain immigrant groups and resulting limiting legislation in the early 20th century; later epochs continued the conversation) [2]. Sources do not offer contemporaneous polling from 1970 tying attitudes directly to the foreign‑born share, only historical linkage and context [2].
6. The low set a baseline for dramatic reversal after 1965
The 4.7% low functioned as a demographic baseline from which post‑1965 immigration growth became striking: by the 21st century the foreign‑born share rose again toward double‑digit levels and, in early 2025, records showed the immigrant population reached new highs before a contested decline later that year (Wikipedia on epochs; CIS and Pew reporting on 2025 highs and later declines establish the swing in recent decades) [2] [4] [5]. Contemporary data debates underscore how politically charged and data‑sensitive these population swings are [4] [5].
7. Contemporary relevance: why the 1970 low still matters
Demographers and policymakers reference the 1970 low when projecting labor markets, fertility and public services because that trough represents a distinct demographic regime—one with lower immigration, different fertility patterns, and different institutional pressures than the immigrant‑rich decades that followed (CBO links net immigration to projected fertility and demographics) [3]. Current debates about 2024–25 population declines show how sensitive policy and public narrative remain to changes in the foreign‑born share (Pew, CIS and other analyses of 2025 swings) [5] [6].
Limitations and open questions — what sources don’t say
Available sources document the national low (4.7% in 1970) and outline broad institutional, political and demographic consequences [1] [2] [3]. Sources do not provide granular ethnographic accounts of everyday cultural change in specific cities in 1970, nor do they quantify how much of mid‑century cultural shifts were caused by the immigrant share versus other forces (suburbanization, deindustrialization, civil rights movement); those causal details are not found in current reporting (not found in current reporting).