From an analysis of the history of immigration management in the U.S.:
The federal departments tasked with immigration responsibilities are so dispersed that it foments balkanization. Within the Department of Homeland Security, the Commissioner of CBP (Customs and Border Protection, the Director of ICE (Immigration and Customs Enforcement), and the Director of USCIS (U.S. Citizenship and Immigration Services) currently are among two dozen DHS officials — including the leadership of Federal Emergency Management Agency, the Secret Service, the Transportation Security Administration, and the US Coast Guard — that report to the DHS Deputy Secretary.
At the State Department, the Assistant Secretary for Consular Affairs (approving visas) reports to the Under Secretary for Management, and the Assistant Secretary for Population, Refugees, and Migration reports to the Under Secretary for Civilian Security, Democracy, and Human Rights.
Within the Department of State, the Bureau of Population, Refugees, and Migration has primary responsibility for formulating policies on population, refugees, and migration, and for administering the US international refugee assistance and admissions programs
The Office of Refugee Resettlement is within the Administration for Children and Families in Health and Human Services.
EOIR (Executive Office for Immigration Review, or immigration courts) reports to the Dept of Justice Deputy Attorney General, and the Immigrant and Employee Rights Section is part of the Civil Rights Division that reports to the Associate Attorney General at the Justice Department.
At the Labor Department, the Office of Foreign Labor Certification (temporary work visa certifications) is housed in the Employment and Training Administration, which is one of 21 agencies that report to the Deputy Secretary. Similarly, the Wage and Hour Division (also for temporary work visa management), reports to the Deputy Secretary of Labor.
As a consequence, immigration leadership responsibilities are nested at the third tier down within these federal departments and are dispersed across eight agency heads. These agency heads report to deputy secretaries that have many other important departmental responsibilities. In other words, there is no clear chain of command for immigration governance.
The dispersed system of immigration governance already begs for reorganization. An expanded governance would best be led by an Interagency Council on Immigration, staffed by top officials from each department. A strong council could coordinate the administration of laws and could recommend policies to ensure more coherent governance. It could even establish a clear chain of command, especially in times of migrant emergencies (such as the 2014 influx of Central American children). That said, a strong council is unlikely due to bureaucratic turf battles.