Well done..

https://www.theguardian.com/business/2017/jan/25/donald-trump-border-wall-mexican-construction-firms-workers-biggest-winners

Building experts estimate barrier could cost $31bn, with most of 40,000-strong workforce from Mexican side of border

By the way I would suggest to build one on the north as well, so we have a proper place to send racists and idiots without a way to escape.