Adriana Alvarado / AP
Rapid response Coahuila state police stand at a checkpoint iin Piedras Negras, Mexico, after a prison break on Sept. 18. Security is among the challenges facing the country.
By Maria Camila Bernal, Telemundo
Where is home to the largest number of Americans living abroad, as well as the world's richest man?
Which country is the United States' third-largest foreign supplier of oil?
Which nation did President George W. Bush call the U.S.' most important bilateral partner?
Which close American ally has lost some 60,000 lives in a U.S.-backed effort to combat violent crime?
The answer to all of the above is Mexico.
But despite the many ties that bind the two countries, the United States' southern neighbor barely warranted a mention during the presidential campaign, and didn't come up once during the third "foreign policy" debate between Gov. Mitt Romney and President Barack Obama.
President Barack Obama and Republican candidate Mitt Romney discuss foreign policy in the third and final presidential debate.
This omission is not lost on many in Mexico.
"At times the United States sees Mexico as an unconditional ally and they see us with the stigma of an undeveloped nation," said Eduardo Rosales, director of the United States-Mexico relations master's program at the National Autonomous University of Mexico (UNAM). "But the United States needs to put their eyes south. It is the most important bilateral relationship in the world."
Some Mexico-related news is grimly familiar to most Americans -- tens of thousands have died in violence since outgoing President Felipe Calderon declared war on the country's drug cartels at the end of 2006.
Mexico's drug war: No sign of 'light at the end of the tunnel'
Mexican cartels funnel between $19 and $39 billion worth of illegal drugs to the United States every year, according to the State Department. The United States, in turn, is a major source of weapons for the cartels.
Mexico's death toll remains stubbornly high and swathes of the country virtually ungovernable despite the Merida Initiative, a $1.9-billion U.S.-funded program aimed at fighting trafficking, organized crime and money laundering.
A vivid example of the shared security challenges came in August when Mexican police officers thought to be working in cahoots with the cartels ambushed and wounded two U.S. agents.
Violence, including the discovery of 49 mutilated bodies near the U.S. border, is reaching new levels in the ongoing drug war in Mexico. NBC's Mark Potter reports.
Oscar Alvarez, a college student in the northern state of Coahuila, alleged that much of the blame for the violence and crime lies with the United States, the world's largest consumer of illegal drugs.
"The demand on drugs is not being controlled ... and Mexico will always be affected," said Alvarez, 22, who has a small printing business to help cover the costs of school. "Whoever wins (the U.S. election) needs to act. I've heard a lot of talk but I haven't seen anything get done."
NBCNews.com's The World is Watching series: Should next US president treat Russia as friend or foe?
That the drugs trade and the hyper-violent crime that surrounds it is a shared problem has not been widely accepted in the United States, according to UNAM's Rosales.
"The problem is the consumption and the things that surround it such as violence and money laundering," he said. "It's a reality that is neglected by the United Sates. But our bloodshed continues to grow."
Cross-border methamphetamine trade booms amid Mexico's 'war on drugs'
It isn't clear how incoming President Enrique Pena Nieto of Institutional Revolutionary Party, which governed Mexico for about 70 years, will deal with the cartels, but indications are that many in country are losing patience with the drug war.
"I'm against the war," former Mexican foreign minister Jorge Casta?eda told NBC News in May. "At six years on, it is beginning to look more difficult to see any kind of light at the end of the tunnel."
Jorge Castaneda, former Mexican foreign minister and NBC News Latin America policy expert, talks about the latest developments in Mexico's drug war where this week 49 mutilated bodies were found near the U.S. border.
Crime and cartels do not define Mexico.
It is one of the United States' most important trading partners. Its economy, the world's 14th largest, grew at 5.5 percent in 2010 and 3.8 percent in 2011, according to the Office of the United States Trade Representative,?despite the global economic downturn. Trade between the United States, Mexico and Canada -- members of the North American Free Trade Agreement -- is worth more than trade within the eurozone.?
NBCNews.com's The World is Watching series: Iran, Israel name checks illustrate America's twin obsessions
A symbol of Mexico's growing international economic prominence is Carlos Slim Helu? a telecoms tycoon with wide-ranging investments including a sizable stake in The New York Times ? who topped Forbes' list of the world's richest people in 2012.
But despite billionaire tycoons and high growth rates, the anemic economy north of the border is hurting Mexico.
Mexico leader's message to US: 'No more weapons!'
Isidoro Peyron, owner of a family-run tile-making business in Pachuca, central Mexico, says the United States' slowdown has hit him directly. Whoever wins Tuesday's election must kickstart the economy for the sakes of both the U.S. and Mexico, he says.
"The next president of the United States needs to reactivate the American economy," said Peyron, 63, who has stopped exporting to the United States. "They are (Mexico's) main commercial partner."
Nevertheless, U.S. trade with Mexico totaled about $500 billion in 2011.?
NBCNews.com's The World is Watching series: Suspicion of US rife as Obama, Romney jab China
The 2,000-mile border between the two countries makes this trade easier, but the easy access also fuels another issue that both unifies and divides the U.S. and Mexico: immigration.
At an estimated 12 million, Mexicans are by far the largest immigrant group in the United States. And around 7 million, or 59 percent of undocumented immigrants, are thought to have come from Mexico.
The Justice Department inspector general found no evidence that Atty. Gen. Eric Holder even knew about the operation that brought more than 2000 guns into Mexico. Fourteen federal law enforcement officials, however, are connected to the botched gun trafficking operation. NBC's Pete Williams reports.
While Obama decreed earlier this year that hundreds of thousands of undocumented migrants who went to the United States illegally as young children would be entitled to remain, the promise he made in 2008 to reform immigration has not been fulfilled.
Meanwhile, there have been more deportations under the Obama administration than during any other presidency in modern times.
But even though Obama has disappointed many for not delivering on immigration reform, the UNAM's Rosales did not hold out hope that Romney will resolve the problems.
"If Romney got to power, there would be zero chances of an immigration reform," Rosales said. "If Obama is elected a second term, it's still hard, but the chances increase."
In his public life, Mitt Romney has said and written little about his ancestors' history in Mexico. It's a little-known fact that there's a whole branch of Mitt Romney's family living south of the border, including his second cousin Leighton Romney, and about 40 other relatives descended from religious pioneers who first traveled to Mexico 125 years ago. NBC's Mike Taibbi reports.
Romney favors a U.S.-Mexico border fence and opposes education benefits to illegal immigrants, as well as offering legal status to illegal immigrants who attend college, although he would support doing so for those who serve in the armed forces.
More Mexico coverage from NBC News
Mike Reyes, who currently resides in Mexico City, lived in Arizona for eight years as an illegal immigrant. He feels the U.S. fails to appreciate what immigrants like himself contributed to the country.
"We hope the situation with Hispanics can be resolved in this election," said Reyes, 45, who works as a driver for the public transportation system despite having a degree in business.
Net Mexican immigration to the United States has stopped growing and may even have declined in recent years, according to a recent study. But with about half of Mexico's population classified as poor, economic realities are likely to continue propelling many Mexicans north for years to come.?
So immigration policies pursued by the winner of the 2012 presidential race will have an impact not only on the United States but Mexico.
More world stories from NBC News:
Follow World News from NBCNews.com on Twitter and Facebook