Drivers headed eastbound on I-40 can't miss this compelling billboard at the 363 mile mark just outside of Knoxville, Tennessee. Paid for by the Roane County Tea Party, the simple and clear message -- America or Obama: You Can't Have Both -- regularly draws cheers and applause from Tennesseans on their way to Roanoke, Virginia.

The Tennesseans have been headed to Virginia each of the last six weekends canvassing door to door to get-out-the-vote for Mitt Romney as part of the Volunteers for Virginia project. They have focused on Roanoke, Virginia, while Texas volunteers have focused on Richmond, Tidewater, and Northern Virginia areas.

Gary Johnston, co-chairman of the Roane County Tea Party, told Breitbart News that the billboard has been up for four months and was the result of a brainstorming session in which the entire board participated:

"It was our board's idea. We kept coming back to the idea 'keep it simple stupid.' It cost us $800 a month plus $1200 to design, ship, and put it up."

For a total investment of $4,400, the billboard has been a very cost effective method of communicating a powerful political message. As Johnston notes:

"I have had calls from all over the world about it. I did an interview with Voice of America. I spent two hours with him a few weeks ago."

Johnston and several members of Tennessee's Roane County Tea Party have spent the past few weekends in Ohio, where they've been going door to door on behalf of the Romney get-out-the-vote effort.

Independent tea party and grassroots activists from across the country will be traveling to the key swing states of Virginia, Ohio, and Florida for the final weekend push before the election. Many will stay to help get-out-the-vote on election day as well.