Polling places across Maine open Tuesday morning as voters get their chance to choose local office holders and decide a pair of statewide referendum questions.

Turnout is expected to be strongest in cities such as Portland, which has seen a record-setting four-way race for the full-time mayor’s position. There also are mayoral elections in Biddeford, Saco, Westbrook, Lewiston and Auburn, as well as other municipal and school board races in those and many other communities.

Statewide turnout is expected to be light, however, because of the absence of any races for statewide or federal offices.

Secretary of State Matt Dunlap said he anticipates a 10 to 20 percent voter turnout statewide. Portland’s City Clerk expected a citywide turnout of about 32 percent, about the same as the last time city voters elected a mayor four years ago.

By comparison, Maine has exceeded a 70 percent turnout in a presidential election year.

The statewide ballot includes a transportation bond and a constitutional amendment.

The bond question asks for voter approval to borrow $105 million for the state’s transportation infrastructure, including $80 million for road and bridge construction, $20 million for ports, harbors, airports, railroads, public transit and bicycle and pedestrian trails, $1 million to improve the pier at Maine Maritime Academy in Castine, and $5 million to upgrade municipal culverts.

The other question on the state ballot would change the Maine Constitution to make it easier for people with disabilities to take part in citizen petition drives. If passed, voters who have physical disabilities would be allowed to use an alternative method of signing a petition, such as using a signature stamp or authorizing another Maine-registered voter to sign on the their  behalf.

Portland’s mayoral race has attracted the most attention in southern Maine, with Mayor Ethan Strimling being challenged by City Councilor Spencer Thobodeau, former school board member Kate Snyder and political newcomer Travis Curran.

It also has attracted a record level of fundraising and spending by the candidates. Three of the four candidates have raised a combined total of nearly $360,000, setting what is believed to be a record for spending in a city election.

The mayoral race also is Maine’s only ranked-choice municipal election.

That means Portland voters can rank the candidates in order of preference. If none of the four candidates gets more than 50 percent of the vote in the first count – the first choice votes – the last-place candidate is eliminated and his or her votes redistributed based on who was designated as each voter’s second choice. That process can repeat until one candidate gets more than 50 percent of the votes.

Voting begins Tuesday at various times depending on the community, but polls open at 7 or 8 a.m. in the vast majority of cities and towns. All Maine polls will close at 8 p.m.

Maine residents 18 and older can still register to vote, even on Election Day.