Over the past couple of decades, cities have been using an interesting and unique tax scheme to help pay for sports stadiums without putting too much of a burden on their own citizens. It is called the hospitality tax, and is only imposed on out of state individuals who stay at hotels, casinos, and other resort or overnight facilities.
So with this in mind, President-Elect Trump could use this same type of taxation scheme and put it towards the Mexican people, and in particular, anyone crossing over the border from Mexico into the United States. And then dedicate that money solely towards the cost of construction for the border wall.
In 2012 over 14.5 million Mexicans came to the United States for non-immigration purposes. This includes those who came across for business, vacations, education, to visit family and friends, as well as any myriad of other reasons. And along the continental borders, Mexican citizens are allowed to cross up to 55 miles into the U.S. without needing anything more than a Border Crossing Card.
During his campaign, President-Elect Trump estimated that it would cost between $8 and $12 billion to build a concrete wall along half of the country's Southern border, with expenses ranging up to $25 billion if you add in technology and additional guard personnel. So with this in mind how much of a tax, or perhaps a better term might be a surcharge, for foreigners crossing into the United States would be practical to use for paying for the construction and upkeep of a wall?
Using $25 billion as the maximum cost, and between 14-15 million visitors from Mexico being the baseline, then a surcharge imposed over a 100-year period would mean that each visitor to the U.S. that crosses the Mexican border would pay an amount of $17.85.
Of course this amount, as well as the duration, could be lessened by finding some of the funding elsewhere... such as in from the Defense budget since defending the borders would become the military's primary job as Trump pulls back resources from installations not really necessary overseas.
In addition to this, President-Elect Trump could lower costs for the Border Patrol by having the military engage their reservists to man and train along the nation's borders.
RIght now there are approximately 639,339 active reservists for the five branches of the military (Including the Coast Guard), and they are required to participate in active duty functions, as well as annual training, for 39 days per year. So if just 5% of this force were dedicated towards using their annual two weeks of continuous duty along the borders, and in the case of the Navy and Coast Guard reserves, along the sea coasts, then that would mean an additional 31,699 trained personnel could supplement the duties of the border guards without adding one cent of additional money as they are already paid for their time on active duty.
In the end there are a thousand different ways Trump can use to not only fund and man a border wall without adding much additional cost from the current budget for its construction and maintenance, but also create a unique way to make Mexico pay for it when their citizens come across the border to visit or make use of our facilities.