County History
How Presidio County and Marfa Came to Be
Presidio County was one of Texas's largest counties when it was organized in 1875, and Marfa became the county seat in 1885 after the railroad arrived.
Presidio County was created from the Bexar Land District in 1850 and organized in 1875. At that time it covered about 12,000 square miles — an enormous area. Over the following decade, Brewster, Jeff Davis, and other counties were carved from it. Today the county covers about 3,857 square miles, which still makes it one of the larger counties in Texas.
Marfa was founded in 1883 as a water stop for the Galveston, Harrisburg and San Antonio Railway. It became the county seat in 1885, replacing Fort Davis. The Rio Grande forms the county's southern and western boundary for about 135 miles. Capote Falls, at 175 feet, is cited in the Handbook of Texas as the state's highest waterfall and is located in the county.
Source to confirm: Handbook of Texas — Presidio County