[3] While condemning the terrorist attacks of 9/11 and providing considerable relief aid to the U.S. after Hurricane Katrina, the Mexican government, pursuing neutrality in international affairs, opted not to actively join the War on Terror and the Iraq War, instead being the first nation in history to formally and voluntarily leave the Inter-American Treaty of Reciprocal Assistance in 2002.

With shared history stemming back to the Texas Revolution (1835–1836) and the Mexican–American War (1846–1848), several treaties have been concluded between the two nations, most notably the Gadsden Purchase, and multilaterally with Canada, the North American Free Trade Agreement (NAFTA).

Once viewed as a model of international cooperation, in recent decades the IBWC has been heavily criticized as an institutional anachronism, by-passed by modern social, environmental and political issues.

Mexico supported U.S. policies in the Cold War and did not challenge U.S. intervention in Guatemala that ousted leftist president Jacobo Arbenz.

Since then, jurisdictional issues regarding water rights in the Rio Grande Valley have continued to cause tension between farmers on both sides of the border, according to Mexican political scientist Armand Peschard-Sverdrup.

After securing the NAFTA treaty that integrated the Mexican and American economies, President Bill Clinton faced yet another foreign crisis in early 1995.

In response, Clinton used executive authority to create a $20 billion loan package for Mexico to restore international confidence in the Mexican economy.

[21] Project Gunrunner was one such efforts between the U.S. and Mexico to collaborate in tracing Mexican guns which were manufactured in or imported legally to the U.S.[22] In 2015, Official reports of the U.S. government and the Bureau of Alcohol, Tobacco, Firearms and explosives (ATF) revealed that Mexican cartels improved their firearm power over that last years, and that 70% of their weapons come from the U.S.[23] The American ATF's Project Gunrunner has as its stated purpose the stoppage of the selling and exportation of guns from the United States into Mexico, with the goal of denying Mexican drug cartels the firearms considered "tools of the trade".

[24] However, in February 2011, it brought about a scandal when the project was accused of accomplishing the opposite by ATF permitting and facilitating "straw purchase" firearm sales to traffickers, and allowing the guns to "walk" and be transported to Mexico.

[26] As of 2013, Mexican students formed the 9th largest group of international students studying in the United States, representing 1.7% of all foreigners pursuing higher education in the U.S.[27] The four-year term of President Donald Trump, who had provoked the ire of the Mexican government through threats against companies who invest in Mexico instead of the U.S., and his claims that he would construct a border wall and force Mexico to fund its construction, caused a decline in the relations of the two countries in the late 2010s.

[33] After Trump signed an executive order in January 2017, mandating construction of the wall,[34] Mexican President Enrique Peña Nieto cancelled a scheduled visit to the U.S.[35] Trump said that Mexico would pay for the construction of the wall, but did not explain how;[36] Mexico has in turn rejected the idea of any Mexican funding.

[36] Peña Nieto listed ten goals he would seek in NAFTA negotiations, notably safeguarding the free flow of remittances, which amount to about $25 billion per year.

In June 2019, a promise of a stricter Mexican asylum program and security tightening to slow the traffic of illegal immigrants into the US averted a possible tariff war between the two countries.

In April 2020, Mexico closed a plant run by an American company for refusing to sell ventilators to Mexican hospitals during the COVID-19 pandemic.

[41] Baja California Governor Jaime Bonilla Valdez ordered the factory closed, because it was providing no essential service to Mexicans.

He said the company contacted Mexico's Foreign Relations Secretary and the American ambassador to prevent the closure order but that he did not cave in to pressure.

[40] On July 7, 2020, President Lopez Obrador visited Washington, D.C., and met with Trump following the signing the United States–Mexico–Canada Agreement trade deal.

[42] In late 2020, multiple human rights groups joined a whistleblower to accuse a private-owned U.S. immigration detention center in Georgia of forcible sterilization of women.

The reports claimed a doctor conducted unauthorized medical procedures on women detained by the U.S. Immigration and Customs Enforcement (ICE).

[45][46] In September 2020, Mexico demanded more information from US authorities on procedures performed on migrants in these facilities, after allegations that six Mexican women were sterilized without their consent.

[47] In October 2020, retired Secretary of National Defense Salvador Cienfuegos was arrested by U.S. officials at Los Angeles International Airport on alleged drug and money-laundering charges.

[52] On February 25, 2021, it was announced that through the Mérida Initiative, the United States and Mexico have forged a partnership to combat transnational organized crime and drug trafficking while strengthening human rights and the rule of law.

[65] During his presidential campaign, Trump threatened to impose 25 percent tariffs on all Mexican goods unless Mexico stopped the flow of immigrants into the United States.

[66] During the second Trump Administration, the CIA plans to expand its role fighting drug cartels in Mexico through intelligence sharing and local training.

[70] Oil and natural gas in particular are traded between the two countries, as well as complex industrial goods such as machinery, electronics, electrical equipment and automobiles.

[72] US investments have changed the economic geography in Mexico, with many border cities such as Ciudad Juárez or Tijuana specializing in trade with the neighbouring country.

[77] The drug trade has made many cartels so rich that they have gained control over many regions of Mexico and are challenging the state's monopoly on the use of force.