An extraordinary work of analysis on immigration:

In the first comprehensive quantitative analysis of the past 140 y of US congressional and presidential speech about immigration, we identify a dramatic rise in proimmigration attitudes beginning in the 1940s, followed by a steady decline among Republicans (relative to Democrats) over the past 50 y. We also reveal divergent usage of positive (e.g., families) and negative (e.g., crime) frames—over time, by party, and between frequently mentioned European and non-European groups.

Most influential words for proimmigration and antiimmigration speeches, in three time periods, when approximating the predicted tone from our classification models with simpler logistic regression models.

Anti-immigration VS Proimmigration

Early (1880 to 1934)   ANTI Chinese, undesirable, exclusion, violation, restriction, permit, dangerous, restrict, smuggled, cheap, excluded, deport, laborers, war, VS PRO country, great, lands, gave, immigrants, entitled, property, relief, agriculture, served, give, rights, protection, glad, industrious

Transitional (1935 to 1972) ANTI aliens, country, illegal, alien, deportation, united, criminals, subversive, fact, deported, America, system, deport, undesirable  VS PRO life, humanitarian, families, migrant, opportunity, contributions, anniversary, citizens, hope, discriminatory, great, children, migrants

Modern (1973 to 2020) ANTI illegally, control, foreign, policy, enforce, entry, people, national, terrorism, illegal, terrorists, stop, smuggling, INS, dangerous VS PRO community, young, immigrant, life, contributions, Hispanic, heritage, dream, victims, Irish, proud, important, Italian, work, treatment, urge