How long did the spanish war last with America?

Although the treaty officially ending it didn't occur until 1899, the actual war itself started and ended in the same year 1898, lasting less than 6 months.

The Philippine insurrection (also called the Philippine War) began in 1899 in the Philippines, is directly related to the Spanish-American War of 1898 and is sometimes considered "part" of the Spanish-American War; but it is not.