President Donald Trump should put his money where his mouth is on the Wall. It's easy for politicians to spend other people's money on projects. If Trump really believes the wall is necessary he should be willing to donate some of his money, possibly his presidential salary, to the wall like many of our fellow Americans are doing. Maybe he could suggest that those running his businesses donate part of the profits to the wall. Trump might try to persuade Congress to match private donations of money or labor. Selling advertising could be practical near urban areas. Perhaps some companies...