Funding U.S.-Mexico Border Barrier Construction: Current Issues [Updated January 3, 2020] [open pdf - 632KB]
From the Document: "The construction of barriers on the U.S.-Mexico borders to control unauthorized crossings has been a matter of significant debate since President Donald Trump made construction of a border wall a key element of his campaign for the presidency. This Insight provides a brief overview of the funding history for these barriers and how the current administration is redirecting federal funds to support construction of additional mileage."
CRS Insight, IN11193
Congressional Research Service: https://crsreports.congress.gov/