I created a visualization in Flourish based on free population and slave populations of Connecticut in 1800. The two variables I was presenting are slave population and free population, and the chart type was chart bar (stacked). Each bar represents a county of Connecticut. And I chose pink to represent the free population, and blue represents the slave population. So that, it shows the two population clearly. Another reason that I used this type of chart is that it is also easy to compare the population between different counties.
The historical question my visualization answer is the free and slave population of Windham, Tolland, New London, New Haven, Middlesex, Litchfield, Hartford, Fairfield in 1800.
I would also use column chart with this data because this type of chart also shows the data clearly.
here is a link to my flourish: https://public.flourish.studio/visualisation/1044318/