The Senate's immigration bill would remake America's economy from top to bottom, and add more immigrant workers in all sectors of society, recent analyses said.

The bill aims to secure the borders, track people overstaying their visas and crack down on employers. But it does not seek to choke off immigration. Indeed, it would increase the U.S. population over the next two decades by 15 million more immigrants than current law, according to the Congressional Budget Office.

In place of the unauthorized workers now commonly found laboring in lower-skilled jobs in the agriculture or service industries, many of these workers would be legal, some of them permanent resident green card holders or even citizens.

The Senate bill offers a 13-year path to citizenship for the estimated 11 million immigrants already here illegally, the most contentious element of the legislation since many House conservatives oppose granting citizenship to people who broke U.S. laws to be here. But that aspect of the legislation has little impact on the overall population size since the people involved are already in the country even if they end up transitioning to legal status. The Congressional Budget Office estimates that some 8 million of them would do just that.

Beyond the changes in numbers, the immigration bill would shift the emphasis of U.S. immigration policy away from family ties and put more weight on employment prospects, education and relative youth. It also would raise ceilings on how many immigrants could come from any one country. And there would be impacts as yet unforeseen as the policies unspool into an uncertain future and economic conditions in other countries affect how many foreigners dream of calling the U.S. home.

Illegal immigration across the border with Mexico would slow, and legal immigration would increase markedly.

"There's not going to be a dramatic change that we will see overnight, but longer-term changes," said Audrey Singer, a senior fellow at the Brookings Institution. "We've got this idea of the policy and then when we put it into practice inevitably there are unintended consequences or unintended trends that develop."