As the 2016 election dramatically revealed, the United States has split into two political nations. In each of those distinct coalitions, the majority Republican or Democratic Party separately controls at least two-thirds of the presidential Electoral Votes, the seats in Congress, and the governorships. That leaves the balance of power with roughly 20 percent of the states and voters—from Ohio to Wisconsin, and Colorado to Arizona—where partisan control is up for grabs and the nation’s political control is determined. For the foreseeable future, significant shifts in the overwhelming numbers on each side seem unlikely.

These dynamics were shown in the past eight years when Washington shifted from Democratic control of the White House and Congress to Republican control of both branches. Elections during that interval revealed that the balance point is so narrow that either party can reign supreme—for the short term, at least. Following the 2008 election, Democrats proclaimed that Barack Obama—the first Democrat since 1964 to win the presidency with a majority of the popular vote and more than 300 electoral votes—had ushered in their political dominance. By June 2009, they had a filibuster-proof 60 Senate seats and a seemingly solid 256-seat House majority.

Just a few months later, their dominance began a steady decline in a succession of steps that hit a painful bottom for them in November 2016. They lost their Senate lock in January 2010, when Republican Scott Brown stunningly won the seat of the late Edward Kennedy of Massachusetts. The following November, House Democrats suffered a cataclysmic 63-seat loss, which Republicans then reinforced during the subsequent redistricting in several key states. In 2014, it was the Senate’s turn, as Democrats suffered a wipe-out with the loss of nine seats and their majority. Finally, Donald Trump won the presidency, when he unexpectedly took Wisconsin, Michigan and Pennsylvania, where Republicans had been shut out since 1988.

Following their 2016 disaster, a Democratic takeover of the House or Senate in 2018 initially was viewed as unlikely. Those prospects in Congress as well as the White House had seemed more likely to improve in 2020. In the early months of the Trump presidency, those calculations shifted. The durability of the Republican coalition seemed as uncertain as the Democrats’ dominance eight years earlier. As always, there are caveats and uncertainties.

Regardless of the outcome of upcoming elections, the political math reveals the challenges facing each party. The United States has evolved to two distinct political coalitions: A Republican hammer-lock in the South and the nation’s heartland, which provides 219 electoral votes in 24 states— all of which are contiguous except for Alaska; A Democratic coalition based on the Atlantic and Pacific coasts, where they hold a solid grip on 203 electoral votes in 16 states; and 116 electoral votes in 10 states in the Great Lakes region and Southwest that are up for grabs.

As the following tables and maps reveal, the split between the two parties has become so clear cut and overwhelming that the numbers are easy to present and describe. This introductory overview provides an essential primer to the profiles of the nation’s top elected officials, plus the states and House districts that they serve, as the 2018 Almanac of American Politics describes in detail. This political evolution dates back a half-century. In those days, Democrats—mostly conservatives--remained dominant in the South, and Republicans could succeed in most other states, with both strong liberals and strong conservatives.

Now that the two parties have lined up on opposite ends of the ideological spectrum, this new status quo likely will remain in place until one party or the other successfully moves into the opposition’s geographical domain. How soon that might happen is among the many challenges facing the Trump presidency and its Democratic opposition. Even with the seemingly entrenched party coalitions of recent years, events have shown that breath-taking change can arrive quickly and unexpectedly.

The following tables describe the components of the two separate party coalitions and the swing groups. The data are vital to understanding political control in the United States, and potential avenues for change. Included below are the presidential results of 2012 and 2016, plus control of governor, Senate and House offices in 10 regions across the nation following the November 2016 election. In each case, the Republican total is followed by the Democratic total. The numbers are based on the actual results of the November 2016 election, prior to subsequent House vacancies and special elections. They ignore the vicissitudes of the casting of Electoral College votes. (The grouping of some states--such as Virginia and Florida—might stir disagreement. But, as the numbers reveal, recent election results have created obvious patterns.)



* Two Senators elected as Independents are grouped as Democrats, with whom they caucus.



More detailed review of the data demonstrates the dramatic sweep of these partisan splits. Of the Republican Coalition’s 24 states, only Florida and Iowa in 2012 voted for the Democratic presidential nominee in either of the past two presidential elections. Only four of those states have a Democratic governor: Louisiana, North Carolina and West Virginia each elected a new Chief Executive in 2015 or 2016, and Montana has a two-term Democratic governor. In the Senate, a scant five Democrats have been elected to those 48 seats. Notably, all five of them are up for reelection in 2018, and each faced the prospect of a significant campaign challenge.

In the House of Representatives, barely one-fourth of the 171 Members from those 24 states are Democrats. Those blue islands in a red sea are easy to identify. Of those 39 Democrats, 20 are African Americans, five are Hispanics, one white represents a black-majority district in Memphis and three Anglos from Texas each represent a heavily Latino district. (In Texas, no Democrat holds a white-majority seat in the 36-member House delegation.) That leaves 10 Caucasian Democrats who represent majority-white districts in the 24 states: Six are from Florida (including one Asian-American), with three from south Florida, two from the Tampa-St. Petersburg area and one from the Orlando area. Three more represent mostly urban districts: Raleigh-Durham, Louisville and Nashville. And one has a mostly rural district in southeast Iowa.

Of the Democratic Coalition’s 16 states, only Pennsylvania and a House district in Maine in 2016 voted for the Republican presidential nominee in either of the past two presidential elections. Six of these states have Republican governors: Massachusetts and the three states of northern New England, New Jersey and Maryland. In the Senate, the only two Republicans from those 32 seats are from Maine and Pennsylvania.

As with the Republican Coalition, there are obvious patterns in the Democratic Coalition. In the House, the six New England states have only one Republican, who is from Maine. In the Far West, California’s 53-seat House delegation has 14 Republicans; two of them serve districts that are on the Pacific coast; only two of the other 12 represent outlying parts of the 16 districts in at least part of Los Angeles County, and none serve in any of the 10 districts in the San Francisco Bay Area. Of the four GOP Members from Washington and one from Oregon, only the Representative from suburban Seattle is from either state’s dominant metropolitan area.

There is a vital anomaly for the six states in the Democratic Coalition’s Mid-Atlantic region. Nearly half of the 77 House Members from those six states are Republicans. They include 13 from Pennsylvania, nine from New York, seven from Virginia, five from New Jersey and one from Maryland. Some of those from Pennsylvania and Virginia have benefited from partisan redistricting. But 22 of those 35 Republicans serve suburban districts where Donald Trump won less than 55 percent of the vote in the 2016 presidential election; 14 of them are from districts where Trump got 52 percent or less. (He won all but five of the 35 districts.)

Of the 10 states that are classified as Up for Grabs, their volatility was evident during the past two presidential elections. In 2012, only Indiana and Arizona voted for Republican Mitt Romney. In 2016, by contrast, this group of ten states gave a small but vital edge to Republican Donald Trump in the Electoral College. Further evidence of the “swing” nature of these states is that all but Minnesota and Colorado have Republican governors, but 13 of their 20 Senators are Democrats.

The narrow Republican edge in the House of Representatives for the 10 states is based chiefly in Ohio, Michigan and Indiana, which have a total of 28 Republicans and 11 Democrats. In effect, those three states plus Florida, Pennsylvania and Virginia (36 Republicans, 20 Democrats) determine which party has the House majority. That pattern might continue following the 2022 redistricting. As shown earlier, those six states also have been vital to recent presidential election outcomes. These results reinforce that factors other than redistricting account for the Republican strength in the House delegation of those six states.

Following the 2008 election, those six states had 51 Democrats and 46 Republicans in the Democratic-controlled House. The huge turnover in the 2010 election shifted 21 of those seats to the Republicans, with a five-seat GOP gain in both Ohio and Pennsylvania and at least a two-seat gain in each of the other four states. Strikingly, that 67- to 30-seat Republican control in those states barely shifted following the 2012 redistricting and the three subsequent elections. The 2016 results yielded a 64- to 31-seat advantage for Republicans. (The states have lost two House seats as a result of reapportionment shifts between the states.)

Only a handful of House districts in those six states have been competitive since 2012, even though many of them have been competitive in presidential elections. Two House seats in those six states have shifted party control since 2012: In Florida and Virginia, Democrats gained one seat in each state, which resulted largely from their unusual court-drawn mid-decade redistricting in 2016. No other House seats have changed party control in the four other states since 2010. One other point is worth noting for those six states: Of those 31 Democratic-held House seats, each is in a large metropolitan area— either in a dominant city or close-in suburbs. Republicans control all of the exurban and rural districts in the six states.

The 10 states that we classify as Up for Grabs have provided much of the battleground for recent presidential elections. Similar patterns have also applied in congressional results. In Senate elections in 2016, Republican victories in competitive contests in Ohio, Indiana, Wisconsin and Arizona were instrumental in the party’s retaining control. For 2018, the fate of Democratic incumbents in Ohio, Michigan, Indiana, Wisconsin and Minnesota, plus the Republican Senators in Nevada and Arizona, will be crucial to the outcome of Senate elections.

In the House, many Democrats expect that their best opportunity to regain control will come in 2022 following the decennial Census. Their prospects will be substantially influenced by whether they can replace five Republican governors in the Midwest battleground--each of those six states except for Minnesota. Not coincidentally, Republicans since 2010 have controlled the state House and Senate in four of those five states: Ohio, Michigan, Indiana and Wisconsin. Prior to 2010, Democrats had control of the House in each of those four states, plus the Senate in Wisconsin.

As for the Senate, Republicans have an obvious benefit, given that each state gets two Senators regardless of its size. Their coalition is based in 24 states, while the Democratic Coalition is in only 16 states. Given that Democrats are at risk in 2018 of losing their remaining five Senators in the 24 states of the GOP coalition, (while Republicans have only two Senators in the 16 states of the Democratic Coalition), that increases the imperative for them to hold firm with their 13 (of 20) Senate seats in the “Up for Grabs” Great Lakes and Southwest states. Of the latter group, four Democrats and two Republicans face potentially competitive reelections in 2018. (For the purpose of this review, the “Independent” Senators from Maine and Vermont are listed with Democrats, with whom each receives committee assignments and is included in the party caucus.)

A similar point applies in the House to many of the 55 Republican-held seats in the 16 states of the Democratic Coalition. Democrats’ opportunities to increase their seats in New York, New Jersey and California—in addition to Florida, Pennsylvania and Virginia—are essential to control of the House.

In politics, of course, change is constant and nothing remains the same forever. A half-century ago, Democrats controlled the South and Republicans were dominant in New England. Just as Republicans benefited in 2016 when Donald Trump climbed over the “Blue Wall” in what had been viewed as Democratic strongholds, Democrats in Congress need to find the keys to open the locks in states and districts that have slipped from their control in shifts between the Two Nations.

The 2018 edition of the Almanac of American Politics debuts on August 21. For more insights, including profiles of all Members of Congress and the governors, order your copy of the Almanac from