Place the rice in a large bowl and add cold water to cover by 3 inches. Swirl the rice around with your fingers until the water becomes cloudy, then pour through a strainer to drain. Repeat the process until the water remains clear. This will take 4 to 6 rinsings.
Place the rice in a large, heavy pot. Add enough water to cover the rice by 3/4 inch (about 2 1/2 cups). Stir in the salt and butter and bring the rice to a boil over high heat. Tightly cover the pan, reduce the heat to low, and cook the rice until tender, about 18 minutes, but check after 15 minutes: If the rice is too wet, set the cover ajar to allow some of the liquid to evaporate; if too dry, add 2 to 3 tablespoons water. Remove the pot from the heat and let the rice stand, covered, for 5 minutes. Fluff it with a fork and set aside.
Meanwhile, prepare the flavorings. Heat the oil in a large sauté pan over medium heat. Add the bacon and cook until lightly browned, about 4 minutes. Pour off all but 2 tablespoons fat. Add the onion, garlic, bell peppers, corn, both raisins, and the parsley. Cook until the onion begins to brown, about 5 minutes. Stir the rice into the vegetable mixture and cook until thoroughly heated, about 2 minutes. Correct the seasoning, adding salt and black pepper as needed.