Columbia subject headings:
Canada--Emigration and immigration--History--21st century.
Immigrants--Canada--History--21st century.
Immigrants--United States--History--21st century.
United States--Emigration and immigration--History--21st century.
Harvard subject headings:
Canada--Emigration and immigration--History--21st century.
Immigrants--Canada--History--21st century.
Immigrants--United States--History--21st century.
United States--Emigration and immigration--History--21st century.
Princeton subject headings:
Canada--Emigration and immigration--History--21st century.
Immigrants--Canada--History--21st century.
Immigrants--United States--History--21st century.
United States--Emigration and immigration--History--21st century.