The North American Union (NAU) is a theoretical continental union of Canada, Mexico and the United States similar in structure to the European Union, sometimes including a common currency called the Amero. Officials from all three nations have said there are no government plans to create such a union, although the idea has been discussed and proposed in academic and scholarly circles, either as a union or as a North American community as proposed by the Independent Task Force on North America. The formation of a North American Union has been the subject of various conspiracy theories.
Since at least the mid-19th century, numerous concepts for a continental union between Canada, Mexico and the United States, often including Caribbean, Central American and South American countries, have been proposed, such as the North American Technate and the Free Trade Area of the Americas. In contrast, details of the North American Union concept emerged not from proponents, but from critics of the idea.
These details emerged when critics identified what they perceived to be the true goals of the Security and Prosperity Partnership of North America (SPP). When the SPP was founded by the governments of Canada, Mexico and the United States in March 2005, some critics claimed it was an attempt to dramatically alter the economic and political status quo between the countries outside of the scrutiny of the respective national legislatures, a critique heightened by the subsequent publication in May 2005 by the Independent Task Force on North America of a report which praised the SPP initiative and called for greater economic integration by 2010. 
While a broad spectrum of observers criticize the secrecy of the SPP and its dominance by business groups, the specific claim that its true aim was to expand the North American Free Trade Agreement (NAFTA) into a North American Union analogous to the European Union (EU), with open borders and a common currency among other features, was being made by the fall of 2006, when right-wing commentators Phyllis Schlafly, Jerome Corsi and Howard Phillips started a website dedicated to quashing what they perceived as the coming North American "Socialist mega-state."
These critics claim the actual goals of the SPP were confirmed by the Task Force,
and by the Task Force’s co-chair American University professor Robert Pastor.
Critics often cite Pastor as being the “father”
of the NAU
and his 2001 book "Towards a North American Community: Lessons from the Old World for the New" has been called a blueprint
for the plan, and includes a suggestion to adopt a common North American currency called the amero.
The SPP was described by the leaders of Canada, Mexico and the United States as being designed to provide greater cooperation on security and economic issues, while the Task Force recommended the "establishment by 2010 of a North American economic and security community, the boundaries of which would be defined by a common external tariff and an outer security perimeter. All three governments deny that there are plans to implement a NAU via the SPP, and the Task Force report said that a North American Community, which would be similar to the European Community which preceded the EU, should not rely on "grand schemes of confederation or union" nor did it suggest a regional government or a common currency. The Task Force’s recommendations included developing a North American customs union, common market, investment fund, energy strategy, set of regulatory standards, security perimeter, border pass, and advisory council, among other common goals.
While the SPP was an initiative carried out at the highest levels of government of the three countries in question, the Task Force was an independent project with no government affiliation organized by the Council on Foreign Relations (U.S.), the Canadian Council of Chief Executives, and the Mexican Council on Foreign Relations.
Nevertheless, the belief that a North American Union is currently being planned and implemented in secret has become widespread, so much so that the NAU has become a topic of debate during the 2008 American presidential campaigns and the subject of various U.S. Congressional resolutions designed to thwart its implementation. Prominent critics such as CNN’s Lou Dobbs and Republican presidential candidate Ron Paul denounced the concept, joined by left-wing groups in Canada, internet blogs, and widely viewed videos and films such as “Zeitgeist.” Corsi’s 2007 book “The Late Great USA: The Coming Merger with Mexico and Canada” also helped bring the NAU discussion into the mainstream. Others who dismiss these beliefs maintain they are the latest example of a long line of misguided conspiracy theories which suggest the United States’ sovereignty is being eroded by a secret cabal of foreign and domestic players.
Some of these NAU skeptics, while expressing concern about the lack of transparency of the SPP, note that this is not evidence of a plot to create a North American Union. “The idea of a regional union that effaces U.S. sovereignty is light-years away from George W. Bush's foreign policy of unilateral action and disdain for international law and institutions.” 
Of the three leaders at the 2005 founding of the SPP (American president George W. Bush, Canadian prime minister Paul Martin and Mexican president Vicente Fox), and the two subsequent leaders (Canadian prime minister Stephen Harper and Mexican president Felipe Calderon), only Fox has voiced support for the ultimate goal of an entity like the North American Union. Before the SPP and since, he has noted the success countries like Ireland and Spain have had in modernizing their economies and bringing higher standards of living for their citizens by joining what is now the European Union and has expressed the hope that Mexico could have a similar experience in a trade body of comparable scope in North America.
However, he has also expressed frustration with the lack of progress towards that goal as issues such as immigration reform proved to be contentious within the United States.
Various positive comments about a North American Union concept and an eventual common currency for the Americas by Vicente Fox, in particular some made during a promotional tour for a book in 2007, have been cited by critics as evidence that the body is in fact being enacted or planned. 
However, the three current leaders of Canada, Mexico and the United States have all characterized the goals of the SPP as being far more modest than the goals Vicente Fox has expressed and what critics have alleged is actually being contemplated.
On August 31, 2007, Internet broadcaster and conspiracy theorists Hal Turner and Ace Sabau claimed to have arranged for a United States Government minted amero coin to be smuggled out of the U.S. Treasury Department by an employee of that organization. Snopes has assessed both Turner's story and the existence of the amero as "False."
The Trans-Texas Corridor was first proposed by Texas Governor Rick Perry in 2002. It consists of a 1,200 foot (366 m) wide highway that also carries utilities such as electricity, petroleum and water as well as railway track and fiber-optic cables. In July 2007, U.S. Representative and candidate for the Republican nomination in the 2008 presidential election Duncan Hunter successfully offered an amendment to House Resolution 3074, the FY2008 Transportation Appropriations Act, prohibiting the use of federal funds for U.S. Department of Transportation participation in the activities of the Security and Prosperity Partnership of North America (SPP). Hunter stated that: "Unfortunately, very little is known about the NAFTA Super Highway. This amendment will provide Congress the opportunity to exercise oversight of the highway, which remains a subject of question and uncertainty, and ensure that our safety and security will not be compromised in order to promote the business interests of our neighbors. Fellow Republican Congressman and presidential candidate Ron Paul brought the issue to mainstream prominence during the December 2007 CNN-YouTube GOP debate, where he rejected the concept and also called it "the NAFTA Superhighway" and, like Hunter, framed it within "the ultimate goal" of creating a North American Union.
The Ministry of Transportation for the province of Alberta displays a diagram on their website that labels I-29 and I-35 as the "NAFTA Superhighway".
Literature
Some form of North American Union is a common trope in science fiction literature. Examples include:
Television