Big government, and big taxes, big regulation, and big programs are a lot more difficult in smaller political subdivisions. From Chris Calton at mises.org:
When the southern states were debating secession in 1861, there was one other proposed secession that almost always gets overlooked in history: New York City. The Mayor of New York at the time, Fernando Wood, saw disunion as an inevitability at the start of 1861, and in a January 6th address to the city council, he advocated New York City’s secession.
“When Disunion has become a fixed and certain fact,” Wood asked the council, “why may not New York disrupt the bands which bind her to a venal and corrupt master — to a people and a party that have plundered her revenues, attempted to ruin her, take away the power of self-government, and destroyed the Confederacy of which she was the proud Empire City?”
Although Wood did cite slavery as among the reasons for the city’s need to secede (he believed New Yorker’s benefited from trading with the slave economy, and the city was home to a respectable number of slave traders who continued to operate their not-entirely-clandestine businesses for places such as Brazil and Cuba), he did not propose joining the Confederacy, which had yet to be formed. He wanted to establish New York City as sovereign entity — the Free City of Tri-insula, referring to the islands of Manhattan, Long, and Staten.
The Common Council agreed with Wood, and the city looked poised to secede. They only changed their position after the bombardment of Fort Sumter, not because they objected to the Confederacy’s actions as much as their desire not to be surrounded by territories that would view them as traitors during the oncoming war.
But New York’s near-secession is an example of what many people in the North — particularly Republicans — feared from secession; they were not worried about severing their nation, but rather that it might dissolve altogether — or at the very least, break into multiple smaller countries. The relatively new Republican Party had grand plans for the country, rife with economic interventions such as infrastructure projects, a transcontinental railroad, a protective tariff, and a homestead act.
The only thing that had prevented such reforms taking place in the past was sectional disagreement on various policies. Southerners, for instance, supported a transcontinental railroad, but they wanted it to be built in the South, and no compromise was ever successfully made. Southerners also supported homestead legislation that would have sold public lands, rather than granting 160 acres for only a standard clerical fee. Infrastructure and economic protectionism were more widely rejected by southerners, and Southern Democrats continually blocked the passage of such bills.
To continue reading: Why Secession Is a Big Problem — For Politicians