The connections between trade and migration are as longstanding as the historic movements of goods and people. The desire for commerce may often be the principal motivation, but the need to send people to facilitate the transactions soon follows. Recognition of this phenomenon was incorporated into the Immigration Act of 1924, which included a provision for aliens who were entering the United States solely to carry on trade between the United States and the foreign state the alien was coming from, pursuant to a treaty of commerce and navigation. Over 80 years later, a comparable provision of immigration law continues to enable foreign nationals, now known as "treaty traders" and "treaty investors," to enter the United States. In addition to the specific treaty trader/investor provisions of immigration law, there are often broader immigration issues raised in the context of the recent free trade agreements (FTAs). These issues include whether FTAs should contain provisions that expressly expand immigration between the countries as well as whether FTAs should require that the immigrant-sending countries restrain unwanted migration (typically expressed as illegal aliens). The question of whether the movement of people—especially temporary workers—is subsumed under the broader category of "provision of services" and thus an inherent part of any free trade agreement also arises. Even in FTAs that do not have explicit immigration provisions, such as the U.S.-Dominican Republic-Central America Free Trade Agreement (DR-CAFTA), there is a debate over the effects that FTAs may have on future migration. This report opens with an overview of the specific elements of immigration law and policy that are germane to trade-related immigration and follows with a summary of the recent FTAs that include changes to U.S. immigration law. An analysis of research on the interaction between trade and migration is discussed, with caveats on the limitations of such analysis. The report concludes with a set of immigration policy questions that arise in the context of FTAs. As a prologue to any discussion of the nexus of immigration and trade, it is important to acknowledge two key points of departure in policy making on these issues. Foremost is what branch of government—the legislative or executive—takes the lead in setting the policy. Secondly, is whether policies are set unilaterally and without special consideration of other countries or are developed bilaterally or multilaterally. Although Congress has the ultimate Constitutional authority to regulate interstate and foreign commerce, it has shared the authority with the executive branch. The executive branch takes the lead in negotiating trade agreements under strictly defined conditions. Congress considers legislation implementing the trade agreements, according to the Trade Act of 1974, as amended. Immigration policy, on the other hand, is traditionally spelled out by the Congress, not the executive branch. Congress has not shared its authority over immigration and naturalization law with the executive branch to the extent it has done so with trade policy. Bilateral and multilateral agreements with specific countries, a staple of trade negotiations, are quite rare in U.S. immigration policy. When the Immigration Amendments of 1965 replaced the national origins quota system (enacted after World War I) with per-country ceilings, U.S. immigration policy shifted to one that was applied neutrally across the countries of origin. Not only did the admission of legal permanent residents (LPRs) become country-neutral at that time, but formal bilateral guest worker programs, such as the Bracero Program with Mexico, ended as well. Foreign nationals seeking to come to the United States temporarily rather than to live permanently are known as nonimmigrants. These aliens are admitted to the United States for a temporary period of time and an expressed reason. Currently, there are 24 major nonimmigrant visa categories, and 72 specific types of nonimmigrant visas issued. These visa categories are commonly referred to by the letter and numeral that denote their subsection in the Immigration and Nationality Act (INA). Several visa categories that are designated for business and employment-based temporary admission are discussed below, as they are the most likely to correspond to trade-related temporary immigration. To qualify as an E-1 treaty trader or E-2 treaty investor, a foreign national first must be a citizen or national of a country with which the United States maintains a treaty of commerce and navigation. The foreign national then must demonstrate that the purpose of coming to the United States is one of the following: to carry on substantial trade, including trade in services or technology, principally between the United States and the treaty country; or to develop and direct the operations of an enterprise in which the national has invested, or is in the process of investing a substantial amount of capital. Unlike most nonimmigrant visas, the E visa may be renewed indefinitely. The regulations describe substantial trade as follows: Substantial trade is an amount of trade sufficient to ensure a continuous flow of international trade items between the United States and the treaty country. This continuous flow contemplates numerous transactions over time. Treaty trader status may not be established or maintained on the basis of a single transaction, regardless of how protracted or monetarily valuable the transaction. The regulations define the related concept of principal trade as "when over 50 percent of the volume of international trade of the treaty trader is conducted between the United States and the treaty country of the treaty trader's nationality." For treaty investors, the investment must be sufficient to ensure the successful operation of a bona fide enterprise, and the investor must have control of the funds. Uncommitted funds in a bank account or similar security are not considered an investment. The investor must be coming to the United States to develop and direct the enterprise. If the applicant is not the principal investor, he or she must be employed in a supervisory, executive, or highly specialized skill capacity. B-1 nonimmigrants are visitors for business and are required to be seeking admission for activities other than purely local employment or hire. The difference between a business visitor and a temporary worker depends also on the source of the alien's salary. To be classified as a visitor for business, an alien must receive his or her salary from abroad and must not receive any remuneration from a U.S. source other than an expense allowance and reimbursement for other expenses incidental to temporary stay. Intracompany transferees who are employed by an international firm or corporation are admitted on the L visas. To obtain an L visa, the alien must be employed in an executive capacity, a managerial capacity, or have specialized knowledge of the firm's product. To qualify as an executive, the regulations state that the alien must direct the management of the organization or a major component or function of the organization and receive only general supervision or direction from higher level executives, the board of directors, or stockholders of the organization. Those considered to be managerial staff supervise the work of other supervisory, professional, or managerial employees, or manage an essential function within the organization. The regulations define "specialized knowledge" as special knowledge possessed by an individual of the petitioning organization's product, service, research, equipment, techniques, management, or other interests and its application in international markets, or an advanced level of knowledge or expertise in the organization's processes and procedures. The major nonimmigrant category for temporary workers is the H visa. The current H-1 categories include professional specialty workers (H-1B) and nurses (H-1C). There are two visa categories for temporarily importing seasonal workers, i.e., guest workers: agricultural workers enter with H-2A visas and other seasonal workers enter with H-2B visas. Temporary professional workers from Canada and Mexico may enter according to terms set by the North American Free Trade Agreement (NAFTA) on TN visas. The law sets numerical restrictions on annual admissions of the H-1B (65,000), the H-2B (66,000) and the H-1C (500) visas. There is no limit on TN visas. The INA requires that employers of H-2 nonimmigrants conduct an affirmative search for available U.S. workers and that the Department of Labor (DOL) determine that admitting alien workers will not adversely affect the wages and working conditions of similarly employed U.S. workers. Under this process—known as labor certification—employers must apply to the DOL for certification that unemployed domestic workers are not available and that there will not be an adverse effect from the alien workers' entry. The H-2A visa has additional requirements aimed at protecting the alien H-2A workers from exploitive working situations and preventing the domestic work force from being supplanted by alien workers willing to work for sub-standard wages. Most notably, the employer must offer the H-2A workers wages according to the "adverse effect wage rate." The labor market test required for employers of H-1 workers, known as labor attestation, is less stringent than labor certification. Any employer wishing to bring in an H-1B worker must attest in an application to the DOL that the employer will pay the H-1B worker the greater of the actual wages paid other employees in the same job or the prevailing wages for that occupation; the employer will provide working conditions for the H-1B worker that do not cause the working conditions of the other employees to be adversely affected; and there is no strike or lockout. Employers recruiting the H-1C nurses must attest similarly to those recruiting H-1B workers, with the additional requirement that the facility attest that it is taking significant steps to recruit and retain U.S. registered nurses. The INA does not require firms who wish to bring L intracompany transfers into the United States to meet any labor market tests (e.g., demonstrate that U.S. employees are not being displaced or that working conditions are not being lowered) in order to obtain a visa for the transferring employee. Foreign nationals obtaining B-1 business visas are not held to any labor market tests, as they must receive their salary from abroad.