DALE WETZELMANNING, N.D. (AP) â¿¿ Shirley Meyer grew up on a ranch north of Dickinson, N.D., and has represented her rural district in the state House for a decade. But when she knocks on doors in her re-election campaign, she sometimes feels like a stranger in her own home. "I was just shocked at how many new people there were," Meyer said during a recent campaign swing through a south Dickinson mobile home park. "I didn't see one North Dakota (license) plate." The oil boom that has transformed North Dakota's economy and reshaped the rolling prairie landscape has also added an element of mystery to next week's election by adding thousands of potential new voters to the region's tiny electorate. And the political suspense is tied to the national question of which party controls the Senate in January. North Dakota's contest is one of several states with Senate contests that have remained tied for months, with no signs of clarifying before Tuesday's election. A handful of them, such as Montana's Senate race one state west, may not even be resolved then. Republicans are still looking to gain four seats they need to win the Senate majority if President Barack Obama wins reelection, three if GOP presidential hopeful Mitt Romney prevails. Workers from all over the country have pouring into western North Dakota for jobs in the booming Bakken oil shale region. Dickinson, a city of 16,000 that didn't grow at all between 1990 and 2000, is now surging past 20,000 residents, with acres of new temporary housing. By one state measure, the number of oilfield workers has increased from 5,600 to 14,000 since the last presidential election. And many of the new arrivals are eligible to vote. What that means for North Dakota politics, or individual candidates, is anyone's guess.