What were the causes and effects of the Spanish American war?

One of the major causes of the Spanish-American War was yellow journalism. Cuban rebels were assaulting Spanish installations in the country in order to gain their independence. American journalists, trying to sell newspapers, printed stories about the insurrection claiming that the Spanish soldiers were brutal against the poor Cuban rebels, including women and children. Some of the journalists who went to Cuba did not find any war crimes.  Frederic Remington, a noted Western artist, was sent there by William Randolph Hearst. When Remington said that he did not find any atrocities, Hearst wired back that Remington would supply the pictures, and Hearst would supply the war. This war was sold to the American people as America standing up for human rights.  
The real reason for this war had to do with imperialism. Already the United States had gained the island nation of Hawaii, after pineapple and sugar growers overthrew the Hawaiian queen. The United States wanted to get in on the imperialistic fever which had gripped the Western world in the latter half of the nineteenth century. They saw the Spanish empire as being weak and something the American military could bully. The American battleship Maine was sent to Havana Harbor in order to preserve order and to ensure that no further damages were done to American property in the area. When the Maine exploded, it was considered an act of war by Spain, when in reality it was probably an internal explosion caused by a faulty boiler. Divers cleaning the harbor later reported that the explosion which sunk the vessel left a hole consistent with an internal explosion, and not the attack from a mine that the U.S. government claimed at the time.  
The greatest effect of the war was that the United States gained Guam, Puerto Rico, Cuba, and the Philippines from Spain. The Philippines would be harder to subdue, because the Filipino rebel Emilio Aguinaldo wanted to rule the nation himself, and he fought against the Americans for three years in a war that would kill more Americans than the Spanish-American War. Another effect was it made Theodore Roosevelt into a war hero, and probably made him the front-runner to be McKinley's running mate in 1900. This would be key as Teddy Roosevelt would go on to become one of America's most influential presidents.