November 1^st, 1833, by act of the Territorial Legislature, Carroll County was erected. The act reads as follows:

All that portion of the county of Izard west of a line commencing at a point on the State line of Missouri, where the range line between Ranges 16 and 17 west strikes the same, running south with said line twelve miles; thence west six miles to the range line between seventeen and eighteen; thence south with said line to the dividing ridge between Crooked Creek and the Buffalo Fork, thence a direct course to the ridge dividing the waters of the Buffalo Fork and Richland Creek; thence with said ridge to the ridge dividing the waters of the Arkansas and White Rivers; thence west with said ridge to Range 25 west; thence north with said line to the ridge dividing the waters of War Eagle and King's River; thence down said ridge to the post road from Izard court-house, to Washington court-house; thence on a north course to the Missouri line, so as to include all the waters of King's River; thence east with said line to the place of beginning, shall be constituted and erected into a new county, to be called and known by the name of Carroll County.END

The name was conferred in honor of Charles Carroll, of Carrollton, a distinguished Marylander, or possibly in compliment to Gov. William Carroll, of Tennessee. The original territory was reduced in 1836, 1842 and 1869, upon the formation, respectively, of Madison, Newton and Boone.

In 1869, in order that Carroll might not be reduced below the constitutional area of 600 square miles, the northern portion of Madison was annexed. With the exception of unimportant changes in the southwestern boundary, the territorial limits have since remained undisturbed.