controversy over whether missouri should be admitted as a slave state, resulted in the missouri compromise of 1820. this specified that louisiana purchase territory north of latitude 36° 30', which described most of missouri's southern boundary, would be organized as free states. territory south of that line would be reserved for organization as slave states. as part of the compromise, the admission of maine (1820) as a free state was secured to balance missouri's admission as a slave state (1820). the growing population in the industrialized north resulted in the house of representatives having more free state votes than slavery votes. to overcome this imbalance, in 1836 the house instituted a "gag rule" forbidding the house from considering any anti-slavery petitions. it was repealed on december 3, 1844.