Why is the GOP so good at ultra narrow wins?

[Skill and Chance]

This is a very good question.  Arguably, the last time the Dems actually won a toss up election was in 1976 (caveat that 2012 was polling as a toss up in the PV with a narrow Obama EC advantage for a long time).  This is especially odd in 2000 in that a candidate from the second largest state got an EV/PV split in his favor, so this isn't a question that begins and ends with geography or gerrymandering at the congressional level.  Possibilities:

1.  There is 2-5% of the electorate that acts like a swing vote but always comes home to the Republican at the last minute.  They act "swingy" enough to consistently fool Democratic campaigns.  Furthermore, these Democratic campaigns may turn off some of their base by tailoring their message toward people who had no intention of voting for them in the first place.

2. Republicans are simply institutionally stronger.  They consistently outperformed election models based on economic fundamentals from 1968 straight through to 2008.  The fact that 2000 was even close ("should" have been a 2008 size Gore win based on economics) and that McCain managed to keep 2008 within single digits suggests that they have a very hard floor.  We have also seen at the state level that apparent ties tend to go in their favor a substantial majority of the time.

3.  2016 was straightforwardly about geographic distribution, with Clinton massively improving in immigrant and knowledge worker heavy California and Texas while falling off just about everywhere else.  Economic models consistently predicted a 1.5-4% Republican PV win, so Clinton actually beat expectations substantially in what was otherwise a Republican version of 2012. 


2012 seems like a watershed event where Democrats finally beat expectations in a presidential election and had obviously better base turnout than the GOP.  Expectations were quite distorted in 2016 due to Trump, but it's important to remember that Hillary actually beat the economic "point spread" by about the same margin Obama did in 2012.  I've said before that the story of the 2010's is more about the left finally pulling even than it is about any robust liberal or conservative majority.  Also, it's not that hard to see a future where Republicans fall into their own geographic packing problem with the inland West shifting out from under them.

[Skill and Chance]

1976 was complicated because it was supposed to be a Carter blowout until the last minute.  2000 was polling as a 2012 sized Bush win until the last month, but that just further underscores how badly Gore performed with massive economic tailwinds at his back. 

There was a long period of Dem overperformance from the 1930's to the 1960's where they seemed to win almost all of the close call elections at all levels of government and had Truman's amazing comeback win in '48.  That is basically where the GOP was from 1972-2012 at the presidential level and from the mid 1990's-present in Congress and at the state level.  Even the 2006 and 2008 Dem waves were quite underwhelming in the historical scheme of things.