I'd like to make a proposal which would defuse the present crisis relating to fourteen million residents of the United States having no right of residence or permit to work.
I suggest that Mexico abandon its sovereignty and allows its entire territory to be amalgamated into the United States, which would thereby gain twenty additional states and a vastly enhanced economy. The upper house in Washington would expand to 140 seats, the lower house would retain the present number of Congressors distributed proportionately across the revised states, the population density of the USA would only rise by 10%, all Mexican law would become obsolete and I suggest each of the new Mexican states should adopt and adjust the existing state law of whichever US state it chooses to model itself on.
Problems fixed, everyone a winner. The minimal number of residents of the expanded United States of America still having no right of residence or permit to work can then be dealt with expeditiously and nobody will have built a wall. The Canadians could even have a referendum on whether they should be included.