US politics with a continuing Atlantic Slave Trade?

What would United States politics, in both internal and external matters (but principally the question of the North-South Divide), look like if the Atlantic Slave Trade had never been suppressed by Britain, either through her not managing to wrest control over the Atlantic Ocean from France and Spain in the 19th century or through British culture somehow not building up an aversion to the institution?


Britain not managing to wrest control over the Atlantic Ocean from France and Spain isn't a viable option. There are too many major factors that would distort the TL beyond the scope of the intended issue. If Britain loses out to Spain and France, then Spanish and French colonial presence in North America will continue to be a threat. There can be no doubt about this: even if British colonials win every land battle in every conflict, if a Franco-Spanish alliance rules the waves to such an extent that it can impose its policy preferences on the entire Atlantic... then Britain will have no choice but to give it all back. And to fork over whatever the enemy demands in addition, too. This is, by definition, a world where Acadia remains French, everything west of the Appalachians remains French, Florida (with its maximum claims) remains Spanish, and British Caribbean possessions are taken away by France and Spain. As such, it is also a world where British colonies in North America remain very reliant on (and in need of) the Crown's protection. So no American Revolution. Naturally, the ATL may well be one where the slave trade remains in operation for much longer, but that's not going to be the most noticable change by a long shot.

If the British cultural shift in attitude in favour of abolition is completely butterflied, the brief Enlightenment idealism that also favoured such a development will be just that: brief. In the USA, it fizzled out in the mid- to late 1790s (whereas in 1776 and even in 1789, a lot of people had assumed that slavery would just be dying out in the decades to come). The thing to keep in mind is that the whole drive for anti-slave trade legislation was formed in that exact period. The abolitionist movement was born in the 1780s, and this movement worked towards the laws against the slave trade.

To kill those laws, you must by definition kill abolitionism as a whole. So there's your answer. We're looking at an ATL where slavery stays far more "normal", and remains unchallenged. Not only does the slave trade continue, but there are basically no Northern abolitionists. (Nor British ones.) We're looking at an ATL where the fledgling abolitionist movement never amounted to anything, and when the French Revolution soured people on the more radical Enlightenment notions, most people just forgot about abolitionism and accepted slavery as a fact of life.

Basically, the effect on US politics, for the forseeable future, would be that the "slavery debate" will be about not allowing slavery up North. Very few people will even consider the notion of outlawing slavery where it exists already. A big issue might be that Northern states would eventually want to prevent slavers from taking slaves up North, but that'll be the extent of it. And if the South wants to expand in order to form more slave states... well, then the political discussion is going to be an economic one. Does this economically benefit the North? If yes, then the North will just back the expansion. If not, then the North will oppose. But this matter will be approached economically, not morally. There will be no great moral drive, no ethical imperative, that moves people to strive towards abolition.

Such a thing could still emerge at a later stage, of course, but it's hard to say how much later.
Illinois and Indiana probably become slave states, while slavery might become entrenched in New Jersey and New York. On the whole, slave power definitely becomes firmly dominant in the United States, as well as diversified because the lower than OTL cost of slaves allow for greater utilization in industry too.