(The Hill) Reid Wilson 09/04/19 06:00 AM Three years after a presidential election that came down to 77000 votes in three Midwestern battlegrounds Democrats and Republicans are eyeing a much larger battlefield ahead of the 2020 contests one that stretches from the picturesque coastline of rural Maine to the high desert of Arizona. Both President Trumps campaign and the Democrats vying to replace him are scrutinizing a political map in flux one in which attitudes and alignments are shifting and new regions are coming into play. As many as a dozen states could be up for grabs next year as economic and international uncertainty pairs with a cauldron of domestic discontent in government. Interviews with two dozen strategists political scientists and observers show the 10 counties across the country that will determine the outcome of the 2020 presidential election. The critical tipping points are as diverse as the American electorate. Some are suburban neighborhoods where both Trump and former President Obama won. Others are longtime Republican strongholds that show signs of slipping. Still others have voted Democratic since the New Deal only to be broken by Trumps historic campaign. Here are the 10 counties that will determine whether Trump gets a second term: Erie County Pa. Settled by Yankee migrants from New England this Pennsylvania manufacturing hub has long resembled Massachusetts or New York more than parts of Pennsylvania founded by Quakers. But in 2016 after years of population exodus Erie County flipped and Trump became the first Republican to win here since Ronald Reagan in 1984. Erie is still theoretically a Democratic domain. About half of voters are registered Democrats and just 36 percent are Republican. Democrats hold five of seven county council seats. But those Democrats are not coastal progressives Pennsylvania politicos say. What you have is a working-class county thats socially conservative" said Terry Madonna director of the Center for Politics and Public Affairs at Franklin and Marshall College. Many Democrats there believe that their party has deserted them and become the party of big cities." In 2016 Trump beat Democratic nominee Hillary Clinton there by 1.6 percentage points about twice the margin by which he won Pennsylvanias electoral votes. In 2008 and 2012 Obama won Erie County by double-digit margins. Democratic success there will be a sign that the party has bridged the divide with its own voters who feel left behind.