The attacks, many involving car bombs, erupted less than a week before Iraqis in much of the country are scheduled to vote in the country's first elections since the 2011 U.S. troop withdrawal, testing security forces' ability to prevent bloodshed.
There was no immediate claim of responsibility, but coordinated attacks are a favorite tactic of al-Qaida's Iraq branch.
Iraqi officials believe the insurgent group is growing stronger and increasingly coordinating with allies fighting to topple Syrian President Bashar Assad across the border. They say rising lawlessness on the Syria-Iraq frontier and cross-border cooperation with a Syrian group, the Nusra Front, has improved the militants' supply of weapons and foreign fighters.
Nearly all of the deadly attacks reported by police officials were bombings.
They were unusually broad in scope, striking not just Baghdad but also the western Sunni city of Fallujah, the ethnically contested oil-rich city of Kirkuk and towns in the predominantly Shiite south. Other attacks struck north of the capital, including the former al-Qaida stronghold of Baqouba and Saddam Hussein's hometown of Tikrit.
The deadliest attacks were in Baghdad, where 15 people were killed. All occurred at around 9 a.m.
In the eastern suburbs of Kamaliya, a parked car bomb exploded in a bus station, killing four and wounding 13. Qassim Saad, an Arabic language teacher in an elementary school nearby, said his pupils began screaming as the explosion shattered windows and sparked panic.
He described a chaotic scene where security forces opened fire into the air upon arrival to disperse onlookers. Wooden carts carrying vegetables, fruit and other goods were overturned and stained with blood, and several nearby buildings and shops were damaged by the blast.
Like many Iraqis after major bombings, he criticized the government for not doing enough to prevent deadly attacks.
"I blame those who call themselves politicians in government (and) the security forces ... for this bad security situation. They are doing nothing to help the people and are only looking out for their benefits," he said.
Two more parked car bombs went off in a parking lot on the road that leads to Baghdad International Airport and killed three people, including a bodyguard of a Shiite lawmaker whose convoy was passing by. The lawmaker escaped unharmed. Sixteen others were wounded.
Four civilians were killed and 15 wounded when an explosion tore through a market and a bus station in the southwestern Umm al-Maalif neighborhood. A roadside bomb went off in the commercial Karrada neighborhood, killing two and wounding 15, while another parked car bomb explosion killed two and wounded nine in western Shurta neighborhood. Five policemen were wounded when their patrol was hit by a roadside bomb in eastern Baladiyat neighborhood.
In and around the ethnically-mixed northern city of Kirkuk, three parked car bombs went off downtown simultaneously - one in an Arab district, one in a Kurdish one, and one in a Turkomen district- killing four civilians and wounding 18. Outside the city, three other parked car bombs killed five and wounded 16. Two of them targeted the house of a Shiite candidate for the provincial elections, but was not harmed.
Kirkuk, about 290 kilometers (180 miles) from Baghdad, is home to a mix of ethnic groups with competing claims to the oil-rich region.
In the former insurgent stronghold of Fallujah, the mayhem began around 6:30 a.m. when a suicide bomber drove an explosives-packed car into a police checkpoint, killing two policemen and wounding six others.
About a half hour later, in the town of Mussayab about 45 kilometers (28 miles) south of Baghdad, a parked car bomb went off in an open market, killing four civilians and wounding 13.
Drive-by shooters armed with pistols fitted with silencers shot and killed a police officer while he was driving his car in the town of Tarmiyah, 50 kilometers (30 miles) north of the capital.
Two more civilians were killed and 14 were wounded when two parked car bombs exploded in the city of Nasiriyah, about 320 kilometers (200 miles) southeast of Baghdad.
One police officer and 13 other people wounded in two separate attacks in the northeastern Diyala province. Five civilians were wounded in Saddam Hussein's hometown of Tikrit, 60 kilometers (35 miles) northeast of Baghdad, when two parked car bombs exploded downtown.
And near the northern city of Mosul, a policeman was killed and two others were wounded while trying to defuse a car bomb. Gunmen also killed a soldier at an army checkpoint in the city.
Local police officials provided details of the attacks, and hospital officials confirmed the casualty tolls. The officials spoke on condition of anonymity because they weren't authorized to release details to reporters.
Although violence in Iraq has fallen from its peak in 2006 and 2007, bombings and other attacks remain common.
The blasts struck a day after a series of attacks left 10 people dead, including a Sunni candidate running in the upcoming provincial elections. The most serious attack Sunday happened when a booby-trapped body exploded among a group of policemen who were trying to inspect it in the street.
Iraqis vote Saturday in what will be the country's first election since U.S. troops withdrew in December 2011. The election, for local-level officials, will be a test of the strength of Prime Minister Nouri al-Maliki's political bloc as well as the ability of security forces to keep the country safe.
Associated Press writers Adam Schreck, Qassim Abdul-Zahra and Sameer N. Yacoub contributed.