The Department of Homeland Security -- Since the DHS guards the borders, they also collect and analyse data about immigration. Check out the Yearbook of Immigration Statistics for the fullest compilation.
Pew Research Center -- An American think tank that provides information on issues, attitudes and trends. The Center comprises a number of relevant projects, including the Pew Hispanic Center and the Pew Social & Demographic Trends. Check out the new report on Key Facts About How the US Hispanic Population is Changing and this one on unauthorized immigrants (2015).
US Dept. of Labor -- Use the search box at the top to search "Immigration". Lots of good links to data and summaries. Check ot this precis on the impact of immigrants on the economy or this table on educational attainment of immigrants.
Cato Institute -- A libertarian think tank, funded by the Koch brothers. Amongst other issues, the Institute focuses on immigration from an economic standpoint. Check out the Cato Studies for data and statistics about immigrants use of welfare.
Center for Economic and Policy Research -- The CEPR was founded by two economists to bring together research findings. Links to reports as well as blogs and op-eds by economists. Use the search box and type "immigration".
NCES -- The National Center for Education Statistics has lots of data about immigrant or non-English speaking children in the schools. Remember that the US is included in the PISA data (Programme for International Student Assessment.)
TRAC Immigration -- A project run by Syracuse University to compile and evaluate government information about immigration. Focuses on border control, immigration benefits (green cards, naturalization, etc.) and the work of the immigration courts.
Law Library of Congress -- The Library produces reports for members of Congress and the public on many issues, including immigration. There are reports about citizenship pathways from various other countries.
DACA (Deferred Action for Childhood Arrivals) Program was created by President Obama by Executive Action in 2012. It was ended by President Trump in September 2017.
Older Information from when the DREAM Act (Development, Relief, and Education for Alien Minors) was proposed. It was considered several times between 2001 and 2012 but was never passed into law.
At least 20 states have passed various laws for the access of undocumented students to higher education. Usually the law provides for in-state tuition to state schools and/or scholarship opportunities. Here are a few examples: