The landmine that killed a US soldier and wounded four occurred early on Saturday near Baiji, 250km (155 miles) north of Baghdad, the US military said.
Two other US soldiers died in south Baghdad on Saturday when their patrol struck a roadside bomb, the US military said.
On Friday, the US command had announced that five other American service members were killed in Iraq the day before.
The eight deaths raised to 2015 the number of US soldiers who have died since the beginning of the Iraq war in March 2003, according to an AP count.
Two police officers died on Saturday when their patrol hit a roadside bomb in the oil-rich city of Kirkuk, 290km (180 miles) north of Baghdad, said police Brigadier Sarhad Qader.
In Baghdad on Saturday, the campaign for the 15 December parliamentary election effectively began as several of the 18 coalitions conducted news conferences to announce their tickets.
Former prime minister Ayad Allawi, a secular Shia and the leader of a broad coalition, said that if his group’s candidates were elected, they would "treat all Iraqi people equally and bring stability, security and a strong leadership" to the country.
Former pime minister Iyad Allawi
announced his group's candidates
On Friday, a Sunni Arab coalition had submitted its list of candidates, joining other political factions in the race and signalling greater Sunni participation in a process Washington hopes will help speed the day when US troops can go home.
The coalitions and an undetermined number of parties and independents met the Friday deadline of filing for the election, when voters select a 275-member parliament to serve for four years. It will be the first full-term parliament in Iraq since Saddam Hussein's regime collapsed after the US-led invasion of 2003.