By 1860 the dissolution of the Whig Party in America had become an accomplished fact, with establishment Whig politicians, former Free Soilers, and a certain number of anti-Catholic populists from the Know Nothing movement flocking to the banner of the fledgling anti-slavery Republican Party.
While 1856 Republican presidential nominee John C. Frémont had met with failure, party gains were made throughout the Northern United States as the sectional crisis over slavery intensified.

Party leaders sought to hold their 1860 nominating convention in the burgeoning Middle Western trade center of Chicago, then a city of some 110,000 people.
The city had no sufficiently large meeting hall, so an appropriation was made for a temporary wood-frame assembly hall – known as the "Wigwam" – to seat ten thousand delegates, guests, and observers.
The rapidly designed and constructed building proved well fit for the purpose, featuring excellent lines of sight and stellar acoustics, allowing even an ordinary speaker to be heard throughout the room.

The Convention commanded the interest and attention of a multitude of curious citizens who crowded the "Wigwam" to the rafters.
Delegations were seated by state and the gathering was virtually devoid of Southern participation, with no delegations attending from the slave states of North Carolina, South Carolina, Tennessee, Arkansas, Georgia, Alabama, Mississippi, Louisiana, and Florida.

Delegation voting strength was loosely based upon the size of each state's congressional delegation, subject to some modification by the Credentials Committee, with the Northeastern delegations of New York (70), Pennsylvania (54), Massachusetts (26), and New Jersey (14) constituting the largest regional block, surpassing the Midwestern states of Ohio (46), Indiana (26), Illinois (22), and Iowa (8).
Some 86 votes were apportioned to the six states of New England.
Slave and border states with substantial delegations under the rules (but with small actual party organizations) included Kentucky (23), Virginia (23), and Missouri (18).
The total of all credentialed delegate votes was 466.
By 1860 the dissolution of the Whig Party in America had become an accomplished fact, with establishment Whig politicians, former Free Soilers, and a certain number of anti-Catholic populists from the Know Nothing movement flocking to the banner of the fledgling anti-slavery Republican Party. While 1856 Republican presidential nominee John C. Frémont had met with failure, party gains were made throughout the Northern United States as the sectional crisis over slavery intensified.
Party leaders sought to hold their 1860 nominating convention in the burgeoning Middle Western trade center of Chicago, then a city of some 110,000 people. The city had no sufficiently large meeting hall, so an appropriation was made for a temporary wood-frame assembly hall – known as the "Wigwam" – to seat ten thousand delegates, guests, and observers. The rapidly designed and constructed building proved well fit for the purpose, featuring excellent lines of sight and stellar acoustics, allowing even an ordinary speaker to be heard throughout the room.
The Convention commanded the interest and attention of a multitude of curious citizens who crowded the "Wigwam" to the rafters. Delegations were seated by state and the gathering was virtually devoid of Southern participation, with no delegations attending from the slave states of North Carolina, South Carolina, Tennessee, Arkansas, Georgia, Alabama, Mississippi, Louisiana, and Florida.
Delegation voting strength was loosely based upon the size of each state's congressional delegation, subject to some modification by the Credentials Committee, with the Northeastern delegations of New York (70), Pennsylvania (54), Massachusetts (26), and New Jersey (14) constituting the largest regional block, surpassing the Midwestern states of Ohio (46), Indiana (26), Illinois (22), and Iowa (8). Some 86 votes were apportioned to the six states of New England. Slave and border states with substantial delegations under the rules (but with small actual party organizations) included Kentucky (23), Virginia (23), and Missouri (18). The total of all credentialed delegate votes was 466.
1860 Republican National Convention