WASHINGTON, D.C. -- President Donald Trump's base of support is currently centered in the evangelical South and rural counties scattered throughout Appalachia and the Midwest, according to June Gallup data analyzed using geopolitical categories developed by the American Communities Project (ACP) at George Washington University.

In most other types of counties across the U.S., Trump's job approval is net negative, with the strongest pockets of disapproval coming from the nation's biggest cities and the dense urban suburbs around them.

While poll data consistently show the president earning well-short of majority job approval nationally, the community-level picture is more nuanced. Trump faces stiff opposition in some places, but in others he continues to be evaluated more positively than negatively.

The list has a fairly clear demographic underpinning.

The counties that support Trump are numerically extensive, but tend to be much more rural. Taken together, the 1,349 counties that make up his strongest base of support -- Rural Middle America, Evangelical Hubs, Working Class Country and LDS Enclaves -- are home to about 35 million potential voters. By themselves, the 47 Big Cities counties hold about 59 million.

Trump's base counties also tend to have median household incomes below the national figure of about $56,000.

The counties in which Trump faces his strongest opposition are generally the most densely populated places in the country, including the Big Cities and Urban Suburbs. These counties, along with the College Towns, also have proportionately more college graduates.

Overall, Trump has seen support slide slightly since the 100-day mark, with his national approval rating falling from an average 41% in the first 100 days to 38% in the month of June. However that data from the first 100 days of his presidency -- from Jan. 20 through April 23 -- showed him earning net-positive reviews in eight county types in the ACP: the four types in the June poll, plus the Exurbs, Middle Suburbs, Military Posts and Graying America.

Trump's slip in those four county types may prove to be significant. They hold distinct parts of the Republican base.

• The Exurbs have higher incomes and more college degrees than the national average and than other GOP communities. They are somewhat representative of the Republicans' establishment core.
• The Middle Suburbs are a set of blue-collar counties based primarily in the Industrial Midwest that swung heavily to Trump in November. The president won them by more than 13 percentage points after Republican Mitt Romney won them by two points in 2012.
• The Military Posts, based primarily near armed forces installations, are reliably Republican and tend to be home to "national security" voters.
• Graying America, counties with lower incomes and large 50-years-or-older populations, consistently vote Republican and are scattered in rural areas across the country.

Trump won the vote in all those county types in November by double digits and, because they are home to 58 million adults, they would likely be key to his re-election hopes.

Gallup's June numbers filtered through the ACP county types also suggest that Trump has lost at least some ground in nearly every type of community since May. Most of these changes were small, however, given the two-point decline in his approval rating among all Americans between May (40%) and June (38%).

Bottom Line

The June numbers indicate that the negative turn in Trump's monthly job approval averages since his inauguration are broad-based, affecting all ACP county types. As a result, he has now fallen below majority approval in some areas that were key to his election. This could affect his viability in 2020 as well as his ability to govern, particularly if it intensifies.