The Aransas River is a short river in south Texas

Texas

Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. It drains an area of the south Texas coastal plains into the Gulf of Mexico

Gulf of Mexico

The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...

. It rises in Bee County

Bee County, Texas

Bee County is a county located in the U.S. state of Texas. Bee County was founded December 8, 1857. As of 2010, the population was 31,861. Its county seat is Beeville. Bee County is named for Barnard E...

 southwest of Beeville

Beeville, Texas

Beeville is a city in Bee County, Texas, United States. The population was 13,129 at the 2000 census. It is the county seat of Bee County...

 and north of Skidmore

Skidmore, Texas

Skidmore is a census-designated place in Bee County, Texas, United States. The population was 1,013 at the 2000 census.-Geography:Skidmore is located at ....

, from the confluence of three creeks

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

: Olmos, Aransas, and Poesta. It flows generally south and southeast in a highly winding course, entering Copano Bay

Copano Bay

Copano Bay is a northwestern extension of Aransas Bay, west of Rockport, Texas in Refugio and Aransas counties. It is supplied with seawater from the Gulf of Mexico via Aransas Bay, and fed freshwater from the Aransas River, Mission River and Copano Creek...

 on the Gulf of Mexico along the Refugio-Aransas

Aransas County, Texas

Aransas County is a county located in the U.S. state of Texas. It is part of the Corpus Christi Metropolitan Statistical Area. As of 2000, the population was 22,499. Its county seat is Rockport. Aransas County was formed in 1871 from Refugio County.-Geography:According to the U.S...

 county line, approximately 10 mi NW of Rockport

Rockport, Texas

Rockport is a city in Aransas County, Texas, United States. The population was 7,385 at the 2000 census. It is the county seat of Aransas County. The coastal community has approximately 8000 citizens. Large windswept live oaks are a dominating feature of the area and the state's oldest live oak,...

.

For some of the period when Texas was a state in Mexico

Mexican Texas

Mexican Texas is the name given by Texas history scholars to the period between 1821 and 1836, when Texas was an integral part of Mexico. The period began with Mexico's victory over Spain in its war of independence in 1821. For the first several years of its existence, Mexican Texas operated very...

, the Aransas formed the southwestern boundary of Texas, separating it from the neighboring Mexican state of Coahuila

Coahuila

Coahuila, formally Coahuila de Zaragoza , officially Estado Libre y Soberano de Coahuila de Zaragoza is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico...

.