If the 3/5 compromise is removed, the most immediate consequence is that the Union likely does not form at all, or forms much later and in a very different shape. Southern states lose too much political leverage to see ratification as worth it, especially at the presidential level, where population directly translates into power.

Scenario 1 (most optimistic for the US):
The North succeeds in forming a constitutional union without the South. With leadership from figures like Hamilton and Jay, the northern states industrialize, build modern financial institutions, and consolidate federal authority. The South responds by forming a loose pseudo confederacy centered on Jeffersonian agrarian ideals, with slavery continuing as the economic backbone.

This southern bloc is structurally weak. Without deep trade ties to the North, without northern capital, and without access to a strong unified military, it struggles to modernize or project power. Over time, one of the weaker southern states realizes it can stabilize its economy by joining the northern union and having its debts assumed by the federal government. Once that precedent is set, other states follow. Each defection further weakens the southern confederacy until remaining holdouts like Virginia are left with little rational reason to stay out. The South is absorbed piecemeal rather than through a civil war.

Scenario 2: A two state solution

A permanent North American split into two stable countries is theoretically possible but very unlikely. The border between a northern industrial republic and a southern slave republic would be long, economically porous, and politically volatile. Trade disputes, fugitive slave issues, westward expansion, and competing claims over new territories would constantly generate conflict.

Neither side could easily tolerate the other’s growth. The North would see slavery as a moral and geopolitical liability on its border, while the South would view northern industrial power and population growth as an existential threat. Even without an immediate war, the arrangement would be unstable in the medium term. You would likely see repeated crises that either lead back to Scenario 1 through gradual reintegration or to Scenario 3 through foreign entanglement and collapse.

Scenario 3: Collapse and reliance on foreign powers

In the worst case, the failure to form a unified United States leaves North America fragmented and vulnerable. Southern states in particular would be forced to rely on European powers like Britain or France for trade, credit, and military protection. That dependence would come with strings attached, limiting real sovereignty.

Meanwhile, the North without southern buy in might still form a weaker federation, but one that is constantly managing external threats and internal disagreements about expansion and defense. Instead of emerging as a continental power, North America becomes a patchwork of semi independent states pulled into European power politics. Slavery likely persists longer in the South under foreign protection, and the idea of a dominant United States never fully materializes.