Created 1858. Organized 1862. Abandoned because of bandit activities in thicket area during the Civil War. Reorganized 1877, with Tilden as county seat. Named for John McMullen (1785-1853), founded with James McGloin of the Irish Colony at San Patricio; President Pro Tempore of the General Council which governed Texas in 1836, on the eve of the Republic.
Of the 254 Texas counties, 42 bear Indian, French or Spanish names. 10 commemorate such colonizers as McMullen and Stephen F. Austin, "Father of Texas". 12 honor Washington and other American patriots. 96 were named for men who fought in the Texas war for independence (15 dying at the Alamo), signed the Declaration of Independence from Mexico, or served as statesmen in the Republic of Texas. 23 have the names of frontiersmen and pioneers. 11 honor American statesmen who worked for the annexation of Texas; 10, leaders in Texas since statehood, including jurists, ministers, educators, historians, statesmen; and 36, men prominent in the Confederacy during the Civil War. Rockwall and 8 others have geographical names. San Jacinto and Val Verde were named for battles; Live Oak and Orange, for trees; and Mason for a fort.