FACTBOX: Indiana and its presidential primary

(Reuters) - Indiana holds its presidential primary on May 6 in a contest that could cement Democrat Barack Obama's front-runner status or deepen concerns about his ability to connect with working-class whites.

Here are a few facts about Indiana and its presidential primary:

* Manufacturing accounts for 20 percent of all Indiana jobs, the highest proportion of any U.S. state. New ventures in pharmaceuticals, biofuels and medical sciences are joining established industries like steel, engines and mobile homes.

* Polls begin to open at 6 a.m. EDT and close by 7 p.m. EDT. Independents and Republicans will be able to vote in the Democratic primary.

* Public opinion polls show Obama and rival Hillary Clinton locked in a neck-and-neck battle in the state. Obama is favored in the industrial northwest, an ethnically diverse, heavily Democratic area that bears many similarities to his nearby Chicago home. Obama, who would be the first black president, also is expected to do well in Indianapolis, home to a large black population.

* Clinton is expected to do well in much of the rest of the state, which is predominantly white and culturally conservative.

* Residents of Indiana are known as Hoosiers. The origin of the word is unknown.

* The Indianapolis 500, held on Memorial Day weekend, is one of the world's best known automobile races.

(Compiled by Andy Sullivan; Editing by Cynthia Osterman)

Sources: U.S. Census Bureau, Almanac of American Politics, Indianapolis Motor Speedway, Reuters