Main articles: Independent Task Force on North America and Security and Prosperity Partnership of North America

In the 20th century the first well-known proposal for a form of North American unification was the North American technate proposed by Technocracy Incorporated in their Technocracy Study Course published first in 1934. The technate would include not only Canada, the U.S., and Mexico, but also Central America, the Caribbean, Greenland, and parts of South America. A technate governing North America remains an objective of the organization.

Most mainstream interest in a North American Union has focused on the Security and Prosperity Partnership of North America (SPP) which finds its origins in proposals for increasing integration in the NAFTA trade bloc during President Bush's first term. Such ideas were commonly called proposals for a NAFTA plus. Former President Vicente Fox of Mexico proposed such an agreement including a NAFTA energy policy, a security NAFTA policy, an advance in financial institutions interchanged, and according to other reports a common market, development fund, migration agreement and new institutions. Fox said such an agreement would take the U.S. and Mexico to a "further integration" and eventually seeking a "convergence" of their economies allowing them to "erase that border".

The attacks of September 11, 2001 turned the focus of integration towards American concerns about security and away from Mexican concerns about immigration and open borders. When the SPP was formed in 2005, a migration agreement was not mentioned focusing instead on synchronizing regulatory policy, reducing congestion at the border, and rationalizing external tariffs. The SPP, however, did include Canadian proposals for reducing congestion at the border.

Prior to the formation of the SPP the Independent Task Force on North America, a project organized by the Council on Foreign Relations (U.S.), the Canadian Council of Chief Executives, and the Mexican Council on Foreign Relations, launched in October 2004, published two documents calling for greater integration between the three countries: Trinational Call for a North American Economic and Security Community by 2010 (March 2005) and its final report Building a North American Community (May 2005).

Their final report, which has been described as "an academic exercise with pretensions of reaching policymakers," proposed increased international cooperation between the nations of Canada, the United States, and Mexico, similar in some respects to that of the European Community that preceded the European Union or the United States' own Articles of Confederation (of sovereign independent states) that preceded the ratification of the United States Constitution which formed a tighter union. The report called for "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." No recommendation was made for a common currency or a supranational institution like the European Union. The report said that a North American Community should not rely on "grand schemes of confederation or union".

In reference to the March 2005 summit in Waco, Texas that established the SPP, the task force's final report stated, "We welcome this important development and offer this report to add urgency and specific recommendations to strengthen their efforts." These specific recommendations include 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.

The formation of the SPP, the reports from the Independent Task Force, and comments from Vicente Fox were cited as evidence for a planned North American Union. Theories about an ongoing plan are predominant on the Internet, especially among bloggers and other writers. Jerome Corsi's columns on WorldNetDaily and Human Events, as well as his best-selling book The Late Great U.S.A.: The Coming Merger With Mexico and Canada, formed the core of NAU conspiracy theories. Corsi himself is often referred to as the leader of the anti-North American Union movement.

The amero is the appellation given to what would be the North American Union's counterpart to the euro. It was first proposed in 1999 by Canadian economist Herbert G. Grubel. A senior fellow of the Fraser Institute think-tank, he published a book entitled The Case for the Amero in September 1999, the year that the euro became a virtual currency. Robert Pastor, vice-chairman of the Independent Task Force on North America, supported Grubel's conclusions in his 2001 book Toward a North American Community, stating that: "In the long term, the amero is in the best interests of all three countries." Another Canadian think-tank, the conservative C.D. Howe Institute, advocates the creation of a shared currency between Canada and the United States. Although then-Mexican President Vicente Fox has expressed support for the idea, when Grubel brought up the idea to American officials, they said they were not interested, citing lack of benefits for the U.S.

On August 31, 2007, conspiracy theorist and Internet broadcaster Hal Turner claimed to have arranged for a United States Government minted Amero coin to be smuggled out of the Treasury Department by an employee of that organization. Snopes has assessed both Turner's story and the existence of the amero as "false".

NAFTA Superhighway

Further information: NAFTA superhighway

Interstate 29 and Interstate 35.

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 U.S. presidential election Duncan Hunter successfully offered an amendment to House Resolution 3074, the FY2008 Transportation Appropriations Act, prohibiting the use of federal funds for 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 Government of Alberta, Canada displays a diagram on their website that labels I-29 and I-35 as the "NAFTA Superhighway".