A precinct is the smallest political unit in American political life; it is a small geographic area that groups voters together. The City of Port Huron, for example, is divided into 10 different precincts. Each precinct will have one location where voters cast ballots each election. A precinct delegate is elected to be a liaison between the local party they belong to and the people who live in their precinct. They may have a role in the state party's political operations as well.
Precinct delegates are perform vital tasks such as promoting their party, taking the pulse of their community on a range of issues, distributing party literature, providing information on voter registration and absentee ballots, and getting out the vote during election years.
Who's eligible to become a precinct delegate? Anyone who is a registered voter, at least 18 years of age, has their permanent address in the precinct they wish to represent, and has filed an Affidavit of Identity form with the county clerk's office no later than 4 pm on the 13th Tuesday before the primary election.
For more information about precinct delegates, check out this short informational packet prepared by the Michigan Bureau of Elections. You can also download the Affidavit of Identity here and contact the county clerk's office here.