What was the Agreement that created a line across the land of the Louisiana Purchase; new states north (with one exception) of the line = free, south = slave

Missouri Compromise.

Explanation:

The Missouri Compromise succeeded in blocking slavery in all new states that was formed from the Louisiana territory. The Missouri Compromise was created in order to maintain balance between slave and non-slave states. With this agreement, the country was divided equally between slave and free states. Missouri is considered as a slave state that gave the south one more state than the north so considering Maine as a free state balanced things again.

what are you options

depending on what kind of map for example a pltical maps works in many ways this iss how it works it shows the areas and places the democratics and the repbulcicans reside for example if   texas chooses trump for president there a republican state and if   califronia chooses hillary there a democratic state.