"Blue wall" is a term that was used by some political analysts and pundits referring to the theory that in Presidential elections in the United States, the Democratic Party had, between the 1992 and 2012 presidential elections, established such an advantage in many, mostly contiguous (hence "wall"), states that the electoral map made a Republican victory an uphill battle from the start. George W. Bush won the 2000 presidential election and the 2004 presidential election, but did not win any of the states in the blue wall. The 2016 election showed this wall was not impregnable, when Republican candidate Donald Trump won 3 previously solidly Democratic states in the area referred to as the Rust Belt, as well as one electoral vote from a previously Democratic fourth state.
The term "blue wall" and "red wall" refer to the colors associated with the Democratic and Republican Parties, respectively.
Ronald Brownstein describes the blue wall as "the 18 states that form the blue wall, a term I coined in 2009" After the 2012 presidential election, Paul Steinhauser called "blue wall […] the cluster of eastern, Midwest and western states that have traditionally gone Democratic." The earliest description of the forces creating the Blue Wall comes from a Houston Chronicle blogger, Chris Ladd. A Republican, Ladd wrote in November 2014 that the seemingly impressive Republican win in the 2014 mid-term elections had overshadowed another trend apparent in the results – a demographic/geographic collapse. The Blue Wall was a Democratic demographic lock on the Electoral College resulting from the Republican Party's (GOP) narrowing focus on the interests of white, rural, and Southern voters. Ladd's analysis became popular when MSNBC commentator Lawrence O'Donnell featured it on a post-election episode of his show The Last Word with Lawrence O'Donnell.
A similar "red wall," behind which lie states solidly Republican, has also been posited to exist. But having fewer votes, it would be theoretically easier for a Democratic presidential candidate to win without breaching it. The Republican party has won just 13 states in each of the last 6 election cycles, totaling 102 electoral votes.
Behind this "blue wall" lay states, many carrying a relatively high number of electoral votes, which appeared to be solidly behind the Democratic Party, at least on the national level, and which a Republican presidential candidate appeared likely to have to write off, seeking a total of 270 electoral votes from other regions. States behind this wall lay generally in the Northeastern United States, and the West Coast of the United States, and included some of the Great Lakes states. In each of the 6 presidential election cycles prior to 2016, the Democratic Party had won 18 of these states (as well as the District of Columbia), totaling 242 of the necessary 270 votes need to win. The "big three" Democratic stronghold states include California, New York, and Illinois.
States falling behind this blue wall generally included those the Democrats had carried since the 1992 presidential election until the the 2016 presidential election that included (in order of decreasing population and followed by number of electoral votes): California (55), New York (29), Illinois (20), Pennsylvania (20), Michigan (16), New Jersey (14), Washington (12), Massachusetts (11), Maryland (10), Minnesota (10), Wisconsin (10), Oregon (7), Connecticut (7), Hawaii (4), Maine (4), Rhode Island (4), Delaware (3), and Vermont (3), as well as Washington, D.C. (3). The last time any of these states cast their votes for the Republican presidential candidate before 2016 was when George H. W. Bush beat Michael Dukakis in 1988. New York, Washington, Massachusetts, Oregon, Hawaii, and Rhode Island have voted Democratic since Ronald Reagan's landslide in 1984. One of these states, Minnesota, has not been carried by a Republican presidential candidate since 1972. (The District of Columbia has voted for the Democratic candidate in every election since it was admitted to the electoral college for the 1964 election.)
It is possible that in a prospective Seventh Party System (period of electoral shift), Nevada (6), Colorado (9), Virginia (13), New Hampshire (4), and New Mexico (5) will join the blue wall, all of which have voted Democratic since George W. Bush's re-election in 2004, as Nevada, New Mexico, and New Hampshire have only voted Republican for George Bush. Iowa was a possible contender, but with Donald Trump's 10-point win there, it is highly doubtful.
The states which Republicans have won in the last 7 cycles include Texas (38), Alabama (9), South Carolina (9), Oklahoma (7), Mississippi (6), Utah (6), Kansas (6), Nebraska (4), Idaho (4), South Dakota (3), North Dakota (3), Alaska (3), and Wyoming (3), giving a total of 102 votes. States with a 6-out-of-7 Republican record include Georgia, North Carolina, Arizona, Indiana, and Montana for a total of 158 electoral votes. Much of the Southern United States are probably safely Republican as well, as 6 other states from that general region have not voted for a Democrat since southerner Bill Clinton in 1996, and the Deep South is solidly Republican in their senators and governors. In a Seventh Party System, it is possible many other states could join the red wall, especially states such as West Virginia, where Donald Trump had his widest margin of victory in 2016.
The Democratic "lock" on these states had been called into question prior to 2016, as several had been competitive in recent elections, and many had Republicans currently holding elected statewide office, generally either senator or governor. Blue wall states with a Republican senator included Pennsylvania, Wisconsin, and Maine. Those with a Republican governor included Illinois, Michigan, New Jersey, Massachusetts, Maryland, Wisconsin, and Maine. In addition to these 18 states, three others, Iowa, New Mexico, and New Hampshire, had only voted for the Republican once in the same 6 election cycles, giving their votes to George W. Bush in either 2000 or 2004. If included in the total, the votes behind the blue wall numbered 257, just 13 short of what is needed to win. In 2016, the blue wall showed some cracks, and went down from 242 electoral votes to 195. Some in the mainstream media, did however suspected the democrats might lose Pennsylvania
Nate Silver had criticized the idea of the blue wall, pointing to a larger "red wall" of states that voted Republican from 1968 to 1988. He argued that the blue wall simply represented a "pretty good run" in elections, and that relatively minor gains in the popular vote could "flip" some of its states to Republican. This was seen in the 2016 election, where voters from manufacturing states traditionally behind the blue wall voted for Donald Trump, providing him the victory in Michigan, Pennsylvania, and Wisconsin.