Whatever the outcome, Iraq took another big step toward becoming a fully democratic and independent nation. But the apparent Sunni dissatisfaction with a proposed constitution makes clear there could still be rough days ahead -- bad news for a US military that hopes it could soon begin to pull out.
Except for several hot spots west of Baghdad, Sunni Arabs came out of their postwar political isolation on Saturday to vote on the draft charter.
Most are thought to have voted "no" because they view the constitution as offering a recipe for the eventual breakup of the country.
But what is vastly more important is that their participation signaled involvement for the first time in the US-sponsored political process, which they previously had shunned since Saddam Hussein's 2003 ouster.
That fact should have answered the prayers of at least one homesick US soldier.
"I hope they have a really big turnout," said Lance Corporal Sam Smithson of Sacramento, California, as he helped guard the entrance of a polling station in Haditha.
"The closer they get to independence, the closer we get to going home," he said.
The absence of any major insurgent attack on a day when the US military anticipated violence was another significant development. Some interpreted that as testimony to the growing competence of Iraq's nascent, 200,000-strong security forces.
But it's the political fallout that will stay.
Sunni Arabs -- for centuries Iraq's ruling class -- lost their domination when Saddam was toppled.
Their boycott of the Jan. 30 election pushed them further into the political wilderness, giving them just 17 seats in a 275-seat parliament. That, in turn, complicated the process of drafting the constitution.
Their participation in this vote provides some hope for a country wracked by a brutal Sunni-led insurgency. But their differences with the Shiite-Kurdish alliance that emerged from the January vote are likely to endure.
Continuing rancor along Iraq's Shiite-Sunni divide delays the emergence of a much-needed power-sharing formula for Iraq -- one in which the majority Shiites and their Kurdish allies can retain their newfound power while the Sunni Arabs gain a measure of political relevance that helps them ease into their new, lesser status.
It is in the middle of this maze of political rivalry, ambition and centuries-old feuding that the US must look for an exit to start bringing home some of its 150,000 troops.
Zalmay Khalilzad, the US ambassador in Iraq, is cautiously optimistic, saying before the vote that if the constitution passes, it will be a key step toward the day when American troops can start going home.
But building up Iraqi forces is equally important, he added.
For now, attention will focus next on elections slated for later this year.
Sunni Arabs have vowed to participate in the December elections, regardless of whether the constitution passes or fails. But their own internal disputes make it unclear how they will go about doing that.
At the heart of the internal division is the absence of a figure around which the Sunni community can rally and the inexperience of most of its political groups.
While the Shiites have Grand Ayatollah Ali al-Sistani, a cleric whose word is gospel to almost every one of them, and the Kurds have 14 years of experience running a mini-state in a self-rule enclave, the Sunni Arabs have neither a spiritual leader nor sound political organization.
Many of their senior politicians are tainted with links to Saddam's Baath party.
"They act more on sectarian impulse than political considerations," said a senior Shiite politician Hummam Hammoudi. "They lack a vision for a new Iraq."
Yet, the Sunni Arabs are about 20 percent of the population and are thought to account for the majority in about four of Iraq's 18 provinces.
If they participate in December elections, seats assigned to those provinces could give them 50 to 60 seats in the next 275-seat parliament. That would allow them to form a bloc to be reckoned with and possibly become a desirable partner with secular Shiites, Kurds and nationalists.
"This political process will only succeed when we, the Sunni Arabs, can join a government with nationalist and non-sectarian forces," said Adnan al-Dulaimi, leader of an umbrella of political and tribal groups. "This is what we aspire to."