Constitution of the State of Texas 1876 Art. 9, § 1. Creation of counties

(1) Within the territory of any county or counties , no new county shall be created with a less area than seven hundred square miles, nor shall any such county now existing be reduced to a less area than seven hundred square miles.  No new counties shall be created so as to approach nearer than twelve miles of the county seat of any county from which it may in whole or in part be taken.  Counties of a less area than nine hundred, but of seven hundred or more square miles, within counties now existing, may be created by a two-thirds vote of each House of the Legislature, taken by yeas and nays and entered on the journals.  Any county now existing may be reduced to an area of not less than seven hundred square miles by a like two-thirds vote.  When any part of a county is stricken off and attached to, or created into another county, the part stricken off shall be holden for and obliged to pay its proportion of all the liabilities then existing, of the county from which it was taken, in such manner as may be prescribed by law.

(2) No part of any existing county shall be detached from it and attached to another existing county until the proposition for such change shall have been submitted, in such manner as may be provided by law, to a vote of the voters of both counties, and shall have received a majority of those voting on the question in each.