"Why Did The Union Fight?"
I’ve always thought there was something about the Lincoln administration’s determination to fight and win the Civil War that was a bit odd. Secession gave the regionally based Republican Party large congressional majorities that wouldn’t exist if southern states had representation in congress. What’s more, the Republican Party’s controversial policy objective of banning slavery from the western territories could have been easily achieved by the much more modest policy of simply ensuring military control over the territories. Some fighting in border states such as Maryland, Tennessee, Missouri, and Kentucky is easy to understand but why try to reconquer the Deep South?
In an interesting new paper (PDF), Zachary Liskow suggests economic motives were at the root:
Speciﬁcally, using voting patterns as representations of the Northern population’s preferences, this paper tests empirically whether the economic motivations of its manufacturing interests might have been important components of Northerners’ support of the decision to ﬁght. The hypothesis that the North had economic motivations for keeping the South in the Union yields a speciﬁc prediction: counties with relatively large amounts of these manufacturing interests should shift their votes from Democrats to Republicans between 1860 and 1864. The reason is the following: the best way to keep the South in the Union before the Civil War was to vote for the Democrats, reducing the likelihood of secession by voting for the party more accommodating to Southern slavery interests. However, the best way to keep the South in the Union during the war was to vote for the Republicans, who were more likely to pursue the war until victory was achieved.
Using county-level census data and voting data from the 1860 and 1864 presidential elections, I ﬁnd that there is a signiﬁcant shift toward the Republicans associated with manufacturing employment. This shift toward the Republicans associated with manufacturing together amounts to 2.25% of voters in Northern states; that is, taking the results literally suggests that 2.25% of Northern voters shifted their votes to the Republicans out of a desire to protect their manufacturing interests by keeping the South in the Union.
The basic story here would be something like northern manufacturing interests wanted to keep the southern client base behind the US tariff wall in order to maintain privileged access to the market rather than compete on a level playing field with British goods.