Quote:
Depending on how you define it, the US took almost a century after the abolishment of slavery to become the leading economic power.
If by almost a century you mean 1-2 decades, then yes.
We likely become the dominate economy regardless. Slavery or lack of had little to do with northern growth from 1870-1900(or post WW2 growth). It was the discovery and use of natural resources(coal, oil, iron) and expansion of railroads that made the US the largest economy. These industries would have grown with or without slavery, not to mention all the new machines(subindustries) that came with the use of oil/coal and high carbon steel.
Add to that, we were competing with China at the time, and their economy was decimated in the late 1800s.
As far as the OP goes, the US probably doesn't look the same without slavery, so it's really hard to say who would own what the US doesn't, but if the US was still located in the Penn to Texas/LA area, then we would have eventually become the largest economy in the world, if for nothing else other than isolation and endless Euro/Asian wars.