Complex sentence: Kansas and the Republican Party owe their mutual existence to the passage of the Kansas-Nebraska Act in 1854, which repealed the Missouri Compromise, which had outlawed slavery above the 36⁰30' latitude in the Louisiana territories.
Split into simpler sentences: Kansas and the Republican Party owe their mutual existence to the passage of the Kansas-Nebraska Act in 1854, which repealed the Missouri Compromise. The Compromise had outlawed slavery above the 36⁰30' latitude in the Louisiana territories.