Earlier quoted context omitted.
The American Revolution produced a slave state. There might have been voting among landed gentry but it was not anything I'd call democracy in 2019
The American Revolution ended slavery in 5 states. North American slavery was a British institution.
This is only somewhat correct. Following the Revolution, some northern states abolished slavery almost immediately and the bulk of the North eliminated slavery by ~1810.
In the South, though, inventions like the cotton gin, westward expansion into the Mississippi river basin, and logistical improvements like steamships brought about significant expansion in the South's slave economy. British slavery (particularly in the Caribbean) was more focused on sugar production. Slavery in the United States was distinct from slavery in the British Empire, the fact that the former used to be part of the British empire notwithstanding.