Suburban voters today can make a big national impact on the presidential race, as the winner of the Republican battle for the nomination remains far from clear.
And voters have a lot of big decisions to make elsewhere on the ballot, too, picking presidential delegates, candidates for Congress and the Illinois legislature, and county board members, as well as deciding several ballot questions.
Decisions today ultimately will set up suburban campaigns in November -- particularly for Congress -- that could be among the most-watched in the country.
Here are some things that will help you get ready to head out to the polls today.
After the polls close, check back at dailyherald.com for full results.
Where do I vote?
Polls throughout the suburbs open at 6 a.m. and close at 7 p.m.
To find out where you should vote, look at your voter registration card. Or you can go online to find your polling place and a sample ballot.
DuPage County:http://dupageelections.com/pages.asp?pageid=228; sample ballot at http://cms.dupageelections.com/pages.asp?pageid=984
What district am I in?
New boundaries, drawn after the 2010 census, mean you might no longer be in the legislative or congressional districts you're used to. Check your voting districts before you go to the polls by plugging your address into an interactive, online map at http://www.elections.il.gov/gis.aspx.
Voters in primaries must declare their political party before receiving a ballot. Depending on party affiliation, the ballot will focus solely on Democratic or Republican candidates. What ballot you pull is public record, but whom you vote for isn't.
Those who just want to vote on referendums can ask for a nonpartisan ballot.
If questions are raised at the polls about a voter's registration or identity, the voter can fill out a provisional ballot. While it is the same as the normal ballot, it will not be counted until the election authority has determined the voter is eligible to vote. The authority has 14 days to determine eligibility, and voters have two days after voting to provide additional information.
No one is allowed to attempt to influence a voter within 100 feet of the polling place, among other rules. Any suspicious or illegal activity can be reported to the Illinois attorney general's office at (866) 536-3496.
Voting for delegates
Illinois Republican delegates -- the people who eventually pick the party's nominee for president at the convention -- are not handed out based on which candidate for president you vote for.
Instead, you can vote for three delegates and three alternates in any combination you want.
Many people vote for the delegates aligned with their favorite presidential candidate. But you could vote for two delegates aligned with one candidate, for example, and one for a different candidate. Republican candidates will win delegates based on which of their people are elected in each congressional district.
The Democratic primary for president is uncontested.
Former Massachusetts Gov. Mitt Romney plans an election-evening event at the Renaissance Schaumburg Convention Center Hotel.
Former Pennsylvania Sen. Rick Santorum will watch Illinois returns from a Best Western hotel in Gettysburg, Penn.
Former House Speaker Newt Gingrich of Georgia will be campaigning in Louisiana in advance of Saturday's primary.
Key congressional races
6th Democrats: Maureen Yates of Barrington vs. Leslie Coolidge of Barrington Hills vs. Geoff Petzel of Lake Zurich
8th Democrats: Tammy Duckworth of Hoffman Estates vs. Raja Krishnamoorthi of Hoffman Estates
9th Democrats: Jan Schakowsky of Evanston vs. Simon Ribeiro of Evanston
10th Democrats: Vivek Bavda of Mundelein vs. Brad Schneider of Deerfield vs. Ilya Sheyman of Waukegan vs. John Tree of Long Grove vs. write-in Aloys Rutagwibira of Hainesville
11th Democrats: Juan Thomas of Aurora vs. Bill Foster of Naperville vs. Jim Hickey of Orland Park
14th Democrats: Dennis Anderson of Gurnee vs. Jonathan Farnick of Woodstock