Some U.S. territories existed only a short time before becoming states, while others remained territories for decades. The shortest-lived was Alabama Territory at 2 years, while New Mexico and Hawaii territories both were in existence for more than 50 years. The entry of several states into the Union has been delayed by complicating factors. Among them, Michigan Territory, which petitioned Congress for statehood in 1835, was not admitted to the Union until 1837, because of a boundary dispute with the adjacent state of Ohio. The independent Republic of Texas requested annexation to the United States in 1837, but fears about potential conflict with Mexico delayed the admission of Texas for nine years. Also, statehood for Kansas Territory was held up for several years (1854–1861) because of a series of internal violent conflicts involving anti-slavery and pro-slavery factions.