Restricting trade and immigration is a toxic. It could damage the economy. Trade is necessary for every nation. It is a means of selling what it has and buying what it needs. There have to be rules and those are contained in the agreements negotiated, like NAFTA.
Some countries run a deficit and that is not necessarily bad and may indeed be a good sign. When, as in the case of US and Mexico, there are many reasons. Firstly, the US has a very strong currency much more valuable than Mexico's. So it is cheaper for American consumers to buy much more of what they want ( avocados, tequila, cars, oil and gas etc.), while the Mexicans cannot afford to buy as much from the US. US/Mexico trade is worth $581 billion+ with a $ 55 billion deficit; US/China has a $659 billion trade with $ 360 deficit and Us /Canada has a $575 billion trade with a $ 15billion deficit. In the case of China, much of what it sells to the US is made by American corporations in China and it is very inexpensive and so shoppers at Walmart and other outlets, get a bargain, buy a lot and the corporations hire workers and make a huge profit and consumers save. The same with Mexico and Canada. Millions of jobs are created on all sides ( the Us/Canada trade is responsible for 9 million jobs in 35 states in the US and 2 million in Canada.
So if, as Trump threatens, he tears up the NAFTA agreement, American consumers will have to pay more for products they need and many millions will lose their jobs. That is why many states are calling on Trump not to restrict trade with Canada. We share a long border and millions travel each year back and forth for shopping and holidays and visiting friends and relatives too.
In the case of Mexico, Trump wants to build a wall, ostensibly to keep out illegal immigrants, many of whom come from various countries in Central and South America and elsewhere and cross the border into the US. He wants the Mexican to pay for the wall but that has been roundly rejected, so he is using the scrapping of NAFTA as a means of forcing the Mexicans to make a deal. That will not happen ( probably, if he had not been so loud and bullying, some deal could have been worked out quietly, but Trump screams insults ( rapists and criminals), rather than negotiate quietly. The $55 billion deficit is due to cheap Mexican goods and the high American dollar. American customers can easily buy Mexican but Mexicans cannot buy American.
China has been the manufacturer to the world for over 20 years. It is a combination of cheap labour and a Chinese government that in the 90s came to realize that it has to open ( to get rich is good, as Deng Chao Ping noted ) up in order to feed its teeming population. Many corporations relocated to China and China flourished ( even Trump wanted to do business there....his clothing line but not hotels), as they produced all manner of goods that were eagerly sought after, from television to clothing to everything. Its trade deficit grew with the US as, not many Chinese consumers could afford to buy American. So Trump used China and the deficit to whip up anger against China, accusing it of, among other things of currency manipulation ( while he and his daughter continue to make products there ).
If Trump goes ahead and try to impose tariffs or any other punitive measures on Canada, Mexico or China, it will be Americans, people and corporations that will suffer, whether it be, by paying more for goods or losing their jobs. He makes policy on the fly, without much thought or information. It may have worked in the election campaign but not as government policies. Ignorance, threats, bullying of trading partners have serious consequences and so the wall, if built will be paid for by American taxpayers; the trade agreements, if they are scrapped will cost American jobs and if tariffs are placed on goods coming into the country, it will be the American consumers who will pay.
Immigration and the 11 million " undocumented" won a lot of support for Trump and won him the White House, but now the reality check. His first attempt to ban immigration from Libya, Yemen, Sudan, Iraq, Iran, Somalia and Syria, by Executive Order was a disaster. It created a nightmare for travellers and not just from these countries and was quickly and successfully challenged in the courts ( District and Appeals , where all 4 judges ruled against the ban ( Trump tried to hide behind an Obama restriction, but failed ). Trump has gone back to the drawing board and a new Order is expected.
In the meantime, there is fear in the land as people are rounded up and deported ( on the grounds that they are criminals, no matter how small the " crime" or how long they have been in the country. Many cities and churches have declared themselves to be " sanctuary" and refusing to go along with the ban or to cooperate with immigration officials. Many fear-stricken people are fleeing across icy fields to the Canadian border, seeking refuge in Canada. Trump's action has led to a petition signed by 1.8 million in Britain, to ban him from a proposed visit and forced a debate in Parliament, whose Speaker "is strongly opposed" to Trump addressing the House of Commons and thus banned from doing so. The Europeans have also been very critical of the " Muslim ban".
The 11 million " undocumented" perform many tasks, from babysitting to gardening to picking crops to construction, to restaurants to working in factories and slaughter houses ( jobs that are "dirty", backbreaking and dangerous and which " Americans" do not want to do. They are a very important part of the work force and already farmers and builders and restaurants etc. are complaining ( even the Trump vineyard has approached the authorities to get " foreign workers" to come in). These are necessary work and the workers pay billions in taxes but do not collect Social Security ( even though they have contributed billions ). Another campaign promise that is having serious consequences.