Yes all that, plus we didn’t have very many people living in the US relative to the abundance of natural resources. The US has been restricting immigration for over 100 years it’s not like just anyone could enter the country. Anyone arguing there were no controls and no restrictions is an obvious disassembler of truth. We should in fact repeal the The Immigration Act of 1990
“The Immigration Act of 1990 (Pub.L. 101–649, 104 Stat. 4978, enacted November 29, 1990) was signed into law by George H. W. Bush on November 29, 1990. It was first introduced by Ted Kennedy in 1989. It was a national reform of the Immigration and Nationality Act of 1965. It increased total, overall immigration to allow 700,000 immigrants to come to the U.S. per year for the fiscal years ’92-’94, and 675,000 per year after that. It provided family based immigration visa, created five distinct employment based visas, categorized by occupation, as well as the diversity visa program which created a lottery to admit immigrants from “low admittance” countries  or countries where their citizenry was underrepresented in the U.S.
Besides these immigrant visas there was also changes in nonimmigrant visas like the H-1B visa for highly skilled workers. There were also cutbacks in the allotment of visas available for extended relatives. The Temporary protected status visa was also created where Congress established a procedure by which the Attorney General may provide TPS to immigrants in the United States who are temporarily unable to safely return to their home country because of ongoing armed conflict, an environmental disaster, or other extraordinary and temporary condition. It specifically benefited citizens of El Salvador.
Other aspects of the act include lifting the English testing process for naturalization which was imposed in the Naturalization Act of 1906″ From Wikipedia