The election for the region's president and 111-seat parliament will test a political establishment that has kept the semiautonomous region relatively safe but faces allegations of corruption and has often clashed with the Arab-dominated central government.
"Today is a revenge day against the main parties," said 44-year-old Shobo Mahmoud shortly after casting his ballot in Sulaimaniyah, 160 miles northeast of Baghdad. "We are suffering from poor public services despite all the promises they made before and the support we gave to these politicians."
The two dominant political coalitions, the Patriotic Union of Kurdistan and the Kurdistan Democratic Party, face a challenge from new opposition alliances seeking to capitalize on alleged misconduct and corruption.
The leaders of the two main coalitions, Iraqi President Jalal Talabani and Kurdish regional President Massoud Barzani, hope their parties can withstand the burgeoning challenge.
The opposition is expected to make some inroads in the parliament. Iraq's election commission said it could take a week to count the results.
The electoral commission announced late in the day it would extend the polling deadline by one hour to accommodate a late, large voter turnout.
Talabani, who was one of the first to cast his ballot, called the election "an important and crucial period and a step forward for a bigger democracy in the region and Iraq."
As security has improved in Iraq, U.S. military commanders have viewed tension between Kurds and Arabs, particularly around oil-rich city of Kirkuk, as one of the greatest threats to Iraq's stability. President Barack Obama has pressured Iraq's central government to be more flexible about sharing power and allowing provincial governments a greater role in decision-making.
But the government is wary about ceding too much authority to the Kurds for fear that they will attempt to secede at some point and take the region's wealth of oil resources with them.
Khalid Najib, a 67-year-old retired teacher from Sulaimaniyah, said he hoped the new government would work with Baghdad to resolve their differences.
"I hope that the next government will be free from tribal and party influences, and adopts no hardline stances against Baghdad and other Arabs in Iraq," Najib said.
But Nesreen Doski, a 31-year-old housekeeper in the Dahuk Province, she did not believe there would be a change in leadership.
"I do not think there will be a new era in Kurdistan or at least a new situation," she said. "I guess the current leaders will keep their posts and they will improve the services being offered to the people."
Security measures have been tightened in the region's three northern provinces - Irbil, Dahuk and Sulaimaniyah - for Saturday's election, and the 2.5 million eligible voters are only allowed to walk or take government authorized buses to polling centers. Polling centers were also set up in Baghdad for Kurdish lawmakers and others to cast their ballots.
"At the end of the day we (Kurds and Arabs) have to solve our problems by ourselves without any outside interference as we are in the same boat and share the same fate," said Mohammed Ahmed, a Kurdish lawmaker.
Iraqi Vice President Adil Abdul-Mahdi said he was encouraged by the elections and hoped the new parliament and government would find ways to ease tensions with Baghdad.
There were a few reports of problems at the polls, said Hindren Mohammed Salih, head of the electoral commission in Irbil.
He said some voters were prevented from casting ballots because their names did not appear on eligible voting rolls and the commission was working on a solution.
The Kurds had hoped to hold a referendum during the local elections on a proposed constitution, which lays claim to disputed areas outside the three Kurdish provinces, including Kirkuk. But national authorities scuttled that plan because Iraq's Arabs view it as an effort to expand Kurdish authority.
The Kurds have also clashed with the central government over a law outlining how Iraq's oil wealth should be divided among the country's religious and ethnic groups, and who has final say in developing the oil fields in the northern region. Iraqi officials say the roughly two dozen deals the Kurds have signed with international oil companies since 2003 are illegal since they were not approved in Baghdad.
Maj. Gen. Robert Caslen, the top U.S. commander in northern Iraq, told The Associated Press he was hopeful that after the elections the Kurdish and Iraqi central governments would renew efforts to resolve the dispute.
"My challenge is that I am stuck in the middle of a tactical challenge of the Kurds and Arabs," he said. "We end up resolving temporary issues that come up."
Caslen said that if the two sides failed to resolve the issues, especially before a scheduled U.S. withdrawal at the end of 2011, the dispute could destabilize the country.
Caslen's area of responsibility includes Kirkuk, where Arab-Kurd tensions have been on the rise, as well as Mosul, where an increase in U.S. combat power in recent months has curbed but not eliminated violence.
Despite increased security measures, a roadside bombing targeting a police patrol in southern Kirkuk wounded five people, including four Iraqi police officers, said Col. Shirzad Moufari.
The Kurds separated from the rest of Iraq after rising up against Saddam Hussein in 1991, aided by a U.S.-British no-fly zone that helped keep the former dictator's armed forces at bay.
Elsewhere in Iraq, two bombs exploded in Fallujah near the area headquarters of the Iraqi Islamic Party, said a police official. Four people were killed and 25 wounded and a building partially collapsed destroying 12 shops, the official said. Police imposed a citywide vehicle ban after receiving report that two more car bombs had been planted in Fallujah, the official said.
In northern Baghdad, a bomb attached to a car exploded in Azamiyah, killing the driver and wounding a bystander, said another police official.
Both officials spoke on condition of anonymity because they were not authorized to release the information.
By Associated Press Writer Yahya Barzanji; AP writers Chelsea J. Carter, Bushra Juhi and Hamid Ahmed in Baghdad contributed to this report