Donald Trump and Hillary Clinton disagree about most everything. On economic policy, their differences couldn't be more stark. Especially important, at least when it comes to the key question of how to jump-start stronger economic growth, are their views on foreign immigration.

Trump is clearly no fan of immigration. Curtailing the entry of migrants is one of his recurring campaign themes. He wants to build a wall between the United States and Mexico, institute a temporary ban on Muslims coming to the country, and, perhaps most important for the economy, he wants the more than 11 million undocumented immigrants in the U.S. to leave.

He's not talking about raids on homes to round up the undocumented and deport them, but he would make their gainful employment prohibitively difficult. He is calling for a national electronic employment verification system, also known as E-Verify.

This would require employers and law enforcement to enter an individual's identification information into an online database that verifies that he or she is a legal resident or legal immigrant with permission to work. Undocumented immigrants couldn't work, making it tough for them to stay here.

Trump would also increase workplace raids by tripling the number of immigration enforcement officers. And he wants to stop any federal funds going to sanctuary cities where undocumented immigrants are largely sheltered from deportation. Philadelphia is a sanctuary city.

Clinton has taken the exact opposite position; she is all-in on immigration. She has endorsed reform such as that in the so-called Gang of Eight legislation, crafted by a bipartisan group of eight U.S. senators. The act passed the Senate in a bipartisan vote in 2013, but stalled in the House and never became law.

This reform includes a path to legalization for certain undocumented immigrants, and it dramatically increases legal immigration by about one million people a year into the U.S. This is double the current number entering the country.

Of higher importance, more educated and skilled foreigners would be allowed in. There would be no cap on permanent green cards for those with graduate degrees in the STEM fields (science, technology, engineering, and math). Temporary visas for both skilled and unskilled workers would also be expanded.

Whose position on immigration is best for the economy?

More immigration, particularly like that envisaged by the Gang of Eight legislation and endorsed by Clinton, is a slam-dunk for the economy. This is according to the Congressional Budget Office, the nonpartisan government agency whose job is to determine the impact of legislation on the economy and the federal budget.

The CBO concluded that reform would boost the nation's GDP - the value of all the things our economy produces - by nearly $3,500 per household a decade after reform became law. This is a big deal, given that the typical American household earns close to $50,000 a year.

Some are worried that more immigrants means fewer jobs for native workers. Not so. Immigrants generally come with few skills and little education or highly skilled and well-educated. Many do menial work in agriculture, construction, and services such as housekeeping and landscaping, taking jobs that would go begging otherwise.

Many other immigrants are among the world's best and brightest. These are the scientists and researchers who drive innovation and technological change. They start new businesses nearly a third more often than native-born Americans do, helping drive future job growth. Such risk-taking is what has historically enabled the U.S. economy to shine brighter than the rest of the global economy.

Those who say that immigrants are a burden on U.S. taxpayers are mistaken. Taxes paid by legal and undocumented immigrants and their children dwarf the costs of the government services they use. The Social Security Administration says that without immigration, the finances of the Social Security system would be even shakier.

Requiring undocumented immigrants to leave the country, as Trump advocates, would also be a blow to the economy. We should do the opposite, as Clinton proposes, and provide a path to legalization for the undocumented.

Many of the undocumented are scared and vulnerable due to their illegal status. They are working at jobs that don't take advantage of the skills they arrived with or have acquired working here, sometimes for many years. As legal residents, they will be empowered to take more productive jobs and earn better pay, allowing them to spend more and pay more in taxes.

I'm hard-pressed to think of an economic policy that would lift the economy by as much as quickly as immigration reform. For sure, some who come here will be a problem, but the overwhelming majority will make our nation a better place.

Mark Zandi is chief economist of Moody's Analytics.