Answer:
Border ruffians
Step-by-step explanation:
The term that refers to pro-slavery activists who crossed the kansas border to vote is border ruffians
Border ruffians was the term that refer to pro-slavery activists which are from the slave trade in Missouri which pass through the state boarder to Kansas territory from the year 1854 to 1860 to imposed the practice of Slavery in the territory.
The Border ruffians were involved negativity in the increase of sectional tensions and are also responsible for the bringing of American Civil war.