One of the arguments in favor of keeping U.S. military bases on Okinawa is that many Okinawans make a living from the bases. If they were gone, these people would lose income. Among this group are people who own the land where some of the bases are located. The Japanese government pays rent to these people, who number about 3,000.
According to an article in the Asahi Shimbun, the total amount of money paid to these "landlords" in 2008 was ¥6.5 billion. That's about 8 percent of all the rent paid to all 34,000 landlords on Okinawa. To put this in perspective, the American military controls about 20 percent of Okinawa's land area (though it only occupies 11 percent), and rent on property accounts for 2 percent of Okinawa's prefectural production (tourism accounts for about 10 percent). Moreover, only 8 percent of the landlords who get money from the bases receive more than ¥5 million a year. More than half the landlords receive less than a million yen, which means most landlords don't make a living from the bases.
The upshot is that the U.S. military controls land that might be more economically viable if the residents of Okinawa controlled it. It's very difficult to develop Okinawa for industry and commercial purposes, which is what many candidates for office in Okinawa want to do, because the position and size of the U.S.-controlled land make it impossible to build continuous transportation networks. Okinawa is the only Japanese prefecture with no rail service. Of course, Okinawa's agricultural sector was greatly diminished by the U.S. military, which confiscated any land it wanted in 1945 (while detaining its owners indefinitely in camps) and then continued appropriating property as it pleased right up until 1972 when the island reverted to Japanese control. Compare this to the U.S. bases on Honshu. Ninety percent of that land was confiscated from the Japanese military during the American occupation. Sixty percent of the land used by U.S. bases on Okinawa is either private property or owned by local municipalities.