1. Democrats from 1852-60 had the remarkable misfortune of consecutive presidents (Pierce-NH, Buchanan-PA), from states their party had regularly won, whose presidency totally destroyed the party in their home state.

2. New Hampshire was deep-blue from 1832-52, Democrats dominated all levels. 54.7%-75% in 6 straight POTUS elections. 1856, Pierce leaving office, Dems lose 45.7%-53.7%; 1860, 39.3%-56.9%. After Pierce, Democrats wouldn't win back NH until 1912.

3. Pennsylvania, always more of a battleground, went D 6 of 8 times 1828-56, only once < 49.9%. Pierce won it by 5, Buchanan by 18. With Buchanan leaving office, Dems lost 37.5%-56.3% in 1860, didn't get the state back until 1936.

4. Less dramatic pattern for several D presidents:

-Ds won NY 4 times in 7 tries thru Cleveland's last race in 1892, got crushed 4 straight times 1896-1908.

-Wilson won NJ in 1912, lost it in 1916, Ds got destroyed there 1920-28.

5. Ds won TX narrowly in 1968 & 76 after LBJ, never again.

Ds won GA 2x under Carter, lost by 20+ in 1984 & 1988, have won it only once since.

Ds lost Arkansas 5 straight times since Clinton; his wife lost it by almost 27 points.

6. Of course, this has happened at times to Rs, even successful ones: CA went GOP 9 times out of 10 from 1952-88, but 1988 was the last time after Reagan that Republicans won the state.

7. Most of those examples involved changing state demographics or issue environments, but there's still no parallel to the total, immediate implosion of the Democrats in NH & PA during the Pierce & Buchanan presidencies.