The U.S. has long viewed Meles as a strong security partner and has given hundreds of millions of dollars in aid over the years. U.S. military drones that patrol East Africa — especially over Somalia — are stationed in Ethiopia. The U.S. goal for Somalia — a stable government free of radical Islamists — is in line with Ethiopia's hopes.
Though a U.S. ally, Ethiopia has long been criticized by human rights groups for the government's strict control, and Meles' legacy is likely to be mixed: positive on the economic development side and negative on the human rights side, said Leslie Lefkow, the deputy director for Human Rights Watch in Africa.
Meles brought Ethiopia out of a difficult period following Mengistu's rule and made important economic progress, she said, but the ruling party has been too focused on building its own authority in recent years instead of building up government institutions.
"I think on the human rights side his legacy will be much more questionable. The country remains under a very tightly controlled one-party rule and this will be the challenge for the new leadership, to take advantage of the opportunity that his death presents in terms of bringing Ethiopia into a more human rights-friendly, reform-minded style of leadership," Lefkow said.
During Meles' election win in 2005, when it appeared the opposition was likely to make gains, Meles tightened security across the country, and on the night of the election declared a state of emergency. Opposition members accused Meles of rigging the election, and demonstrations broke out. Security forces moved in, killing hundreds of people and jailing thousands.
In 2010 Meles won another five years in office while receiving a reported 99 percent of the vote in an election that the U.S. and other international observers said did not meet international standards.
Meles was the leader of a political coalition known as the Ethiopian People's Revolutionary Democratic Front. He was also the longtime chairman of the Tigray People's Liberation Front and has always identified strongly with his party.
"I cannot separate my achievements from what can be considered as the achievements of the ruling party. Whatever achievement there might have been, it does not exist independent of that party," Meles once said when asked what he thought would be his legacy.
Under Meles, Ethiopia saw strong gains in the education sector with the construction of new schools and universities. Women gained more rights. And in the mid-2000s Ethiopia saw strong economic growth, which won Meles international praise. The International Monetary Fund in 2008 said Ethiopia's economy had grown faster than any non-oil exporting country in sub-Saharan Africa.
Despite those gains, Ethiopia remains heavily dependent on agriculture, which accounts for 85 percent of the country's employment. Per capita income is only about $1,000, or roughly $3 a day.
Human rights groups have long denounced Meles' government for its use of arbitrary detention, torture, and surveillance of opposition members. The ONLF, an opposition group that mostly consists of ethnic Somalis, has openly clashed with the government, including in 2007 when Ethiopia sent troops to Somalia to fight al-Shabab militants.
The ONLF said Tuesday that Meles' death is an opportunity for a new government to "initiate a new era of peace, stability, freedom and justice for the people of Ogaden and not to pursue the failed policies of the past."
At the end of 2006, Somalia's U.N.-backed government asked Ethiopia to send troops into Somalia to try to put down an Islamist insurgency. Ethiopian troops moved into the country and captured Mogadishu, but the Somali population rebelled against what it saw as an occupation and Ethiopian forces withdrew in 2009.
Ethiopia again sent troops to Somalia in early 2012 as part of an increased international effort to pressure al-Shabab.