Within a few days after the passage of the Act, hundreds of pro-slavery Missourians crossed into the adjacent territory, selected an area of land, and then united with other Missourians in a meeting or meetings, intending to establish a pro-slavery preemption upon the entire region. As early as June 10, 1854, the Missourians held a meeting at Salt Creek Valley, a trading post three miles (5 km) west of Fort Leavenworth, at which a "Squatter's Claim Association" was organized. They said they were in favor of making Kansas a slave state, if it should require half the citizens of Missouri, musket in hand, to emigrate there, and even to sacrifice their lives in accomplishing this end.