Anti-literacy laws were joined with anti-assembly laws
From my book:
After 1830, driven by isolated rebellion, the need to protect the slaveowners from their large, condensed, male workforces and by the emergence of a new, loud Northern campaigner - the sudden-abolitionist - the anti-literacy laws were joined with anti-assembly laws barring gatherings of free blacks or slaves for any reason, including religious ones, or limiting their numbers, or requiring white supervision.
The minds of free blacks - who were never more than 2 or 3 percent of the black population - and slaves needed to be controlled with greater ferocity than in any other period during the centuries of slavery. Soon, the large slaveowners, as they gathered power over all political opposition in the South, added anti-abolitionist laws to the anti-literacy laws and anti-assembly laws.
The growing power and paranoia of the large slaveowners was reflected, too, in a plan to control the minds of the slaves by allowing Protestant missionaries on the plantation. This “Mission to the Slaves” spanned only two decades but reached into the largest plantations, most of which had been no-go areas for religious instruction in prior years, and taught the slaves the basic tenets: obey your masters and do not steal.
For a reaction set in across the South, led by the slave power, after 1830. The reaction took the form of increased repression of free blacks in the towns and cities, including outright bans (Virginia), head taxes, bans on owning land, deportations, white-sponsor requirements, job limitations, elimination of voting rights, and registration rules. The enhancement in the total control of the slaves by a labyrinth of acerbic laws - anti-literacy, anti-assembly, anti-religion - was one form of the reaction. Free blacks and slaves were banned from preaching or meeting for religious purposes.
Another form was the political domination of the governorships and legislatures across the South, to the exclusion of small slaveholders, independent farmers, and the white tradesmen of the towns and cities.
The reaction also took the form of domination of the churches by the slaveholders, and, in the 1840’s, the Southern churches divorced from their Northern brethren.
In the main, the reaction was a reflection of both the need for control of the isolated workforces on the large plantations and of the sinister, growing political power of the largest slaveowners over other whites in the South and in the halls of the U.S. Senate.
Early roots of the reaction of 1820-1850 include Haiti: the slaves of Haiti fought a war against their French masters for thirteen years, resulting in a victory over Napoleon and Haitian independence in 1803. This frightened the U.S. slaveowners.
Precedent from abroad was bad news: the British ended their ancient Atlantic trade in slaves in 1808.
But most importantly, slave revolts in the South, small in scale but provoking wide scale fear among the slaveholders across the region (Charleston, South Carolina,, 1822; Southampton, Virginia, 1831) drove the reaction and resulted in a storm of furious laws.
Sudden-abolitionist ideas grew into a movement in the North in the 1830’s and were blamed for all new repressive laws and customs.
The political possibilities of extending slavery into the newly-acquired U.S. territories - the entire Midwest by purchase from France in 1803, Texas by war in 1845, California and the territories of Utah and New Mexico by treaty in 1848 - fueled the reaction, too. Were these new territories to be parceled into multiple slave states? The plan for Texas, for example, was that it would eventually house five separate slave states, each, of course, with two U.S. senators. Also, would the Army be used for foreign conquest for the sake of new slave lands, like Texas had been, and would the Navy be used to take Cuba and Central America? These federal subjects are outside the scope of this book, but the effects of the reaction reached down from the height of the U.S. Senate and the war plans of the generals into the slave codes of each state, and from there into the humble, defenseless huts of the slaves.