How The Whig Party Dissolved

 From the 1760s to 1854....there were two political parties in America....the Democratic Party and the Whig Party.

So in 1854, the Kansas-Nebraska Act came into play (passing).  

After this, the northern group of Whigs kinda left the party and went to a newly forming group....the Republican Party. 

Southern Whigs?  There weren't that many, but they mostly went to a quickly formed 'American' Party, and later transformed their small unit to the Constitutional Union Party. 

To note: John Bell ran for the Presidency in 1860 under the Constitutional Union Party....getting around 12-percent of the national vote (mostly southern politically-minded former Whigs).

I would suggest presently, we are in a 1850s mentality and the Republican Party, as it stands today....probably will only exist after 2030 in a marginal form (like the southern Whig folks).