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In the middle of the twentieth century the boundaries of Texas were 2,845.3 miles long, counting the great arc of the Gulf Coast line and only the larger river bends. If the smaller meanderings of the rivers and the tidewater coast line were followed, the boundary was 4,137 miles long and enclosed 263,644 square miles of land and 3,695 square miles of water surface. The location of Texas boundaries has been the subject of international and interstate conflict resulting in treaties, litigation, and commissions from 1736 to the present. Controversy over details continues, as the tidelands controversy and the Chamizal dispute illustrate. In 1995 the state legislature authorized a Red River Boundary Commission to fix the boundary between Oklahoma and Texas, where the still-shifting Red River has frequently changed course and muddied the issue for two centuries.

The eastern boundary was the first to become the subject of controversy and the first to be marked definitely. Both Spain and France claimed the area of present Texas, and by 1716 Spanish presidios at Los Adaes and French trading posts at Natchitoches were separated by only a few miles. In 1736 the commanders at the two outposts agreed on the Arroyo Hondo, a Red River tributary between the Sabine River and Natchitoches, as the boundary between Louisiana and New Spain. After Louisiana was ceded to Spain in 1762, the Arroyo Hondo continued to be regarded as the boundary between the province of Louisiana, a subdivision of the captaincy-general of Cuba, and the province of Texas, a subdivision of the commandancy-general of the Provincias Internas. When the United States purchased Louisiana in 1803, the boundary of the purchase was not defined, but early in 1804 President Thomas Jefferson decided that the territory extended to the Rio Grande. To refute this claim Spain began to investigate her historic claim to the Texas area; Father Melchor de Talamantes and later José Antonio Pichardo made detailed studies of the limits of Louisiana and Texas. While they made academic investigations of the historic boundaries, Spanish forces, in 1806, moved east of the Sabine River to repel an anticipated invasion by Aaron Burr. In order to avert a clash, James Wilkinson and Simón de Herrera, the United States and Spanish military commanders, entered into an agreement that established the Neutral Ground, the area between the Arroyo Hondo and the Sabine River, as a buffer. The makeshift arrangement lasted until 1819, when the Adams-Onís Treaty between Spain and the United States defined the eastern boundary of Texas as beginning at the mouth of the Sabine River, continuing along the west bank of the river to its intersection with the thirty-second parallel, and running due north from that intersection to the Red River. Spain delayed ratification of the Adams-Onís Treaty until 1821. By that time Mexico had declared her independence of Spain and refused to recognize the treaty boundary line. In 1828, after repeated efforts by the United States, the Mexican administration agreed to a survey of the 1819 line, but the Mexican congress refused to confirm the survey treaty until 1832, and then the line remained unsurveyed. Meanwhile, between 1819 and 1836 the Neches River was occasionally advanced as the eastern boundary of Texas. In 1840–41 a survey was made of that portion of the line between the Republic of Texas and the United States from the Gulf of Mexico to the Red River by a joint commission representing the two countries.

On July 5, 1848, the United States Congress passed an act giving its consent to the state of Texas to move its eastern boundary from the west bank of the Sabine River (including Sabine Pass and Sabine Lake) to the middle of that stream, and on November 24, 1849, the Texas legislature enacted a law to that effect. The boundary was unchallenged from that time until November 27, 1941, when Louisiana governor Sam Jones wrote Texas governor Coke Stevenson, asserting that Louisiana's western border was the west bank of the Sabine River. Louisiana's claim rested on United States treaties of 1819 with Spain, 1828 with Mexico, and 1838 with the Republic of Texas, all of which designated the west bank of the Sabine as the boundary of the United States. However, the boundary of the United States at the west bank of the Sabine River was not identical to that of the Louisiana boundary, which extended only to the middle of the river. The state of Louisiana contended that the United States was negotiating on Louisiana's behalf and consequently had no authority to grant Texas the western half of the river in the act of 1848. It was more than twenty-seven years after Governor Jones's letter to Governor Stevenson before Louisiana participated in any legal proceedings. United States district judge Robert Van Pelt, special master for the United States Supreme Court, heard the claims and recommended to the court, in a report filed in May 1972, that the boundary between Texas and Louisiana should be the geographic middle of the Sabine River, Sabine Lake, and Sabine Pass. He also recommended that Louisiana be awarded all islands that existed in the river on April 8, 1812 (the date Louisiana was admitted to the Union), subject, however, to any claims that Texas might make to any such islands by reason of acquiescence and prescription; that all islands formed in the eastern half of the Sabine River since 1812 be awarded to Louisiana; and that all islands formed in the western half of the river since 1812 be awarded to Texas. Sixty-one square miles of the river and lake was involved in the dispute; at stake were more than 35,000 acres of land, four producing oil wells, and $2.6 million in oil lease bonuses collected by Texas. Both states filed exceptions to the recommendations by the special master in July 1972, and after answers to each state's exceptions the Supreme Court was to rule on the master's report. The case was argued before the court in December 1972; the court's ruling came early in March 1973, saying, in effect, that the boundary was the geographic middle of the Sabine River. However, the case was sent back to the special master for further study in regard to the ownership of islands and also to determine the extension of the boundary into the Gulf of Mexico.

Except for the possible claim of the Rio Grande as the western boundary for the Louisiana purchase, the western boundary of Texas had no significance in international relations and practically no mention in Mexican interstate relations before Texas independence. In 1721 the Medina River was considered the boundary between Texas and Coahuila; in 1811 the Nueces River was the boundary between Texas and Tamaulipas. Provisions of the secret treaty of Velasco, which bound the Mexican army to retreat beyond the Rio Grande and Texas not to claim land beyond that river, was the beginning of the Texas claim to the Rio Grande as the western boundary. On December 19, 1836, the First Congress of the republic declared the southern and western boundary of Texas to be the Rio Grande from its mouth to its source and thence a line due north to the forty-second parallel. The Texan Santa Fe expedition of 1841 was an unsuccessful attempt to assert Texas authority in the New Mexico area embraced in that land claim. Texas claimed the same western limits after annexation. The treaty of Guadalupe Hidalgo (1848) affirmed the Rio Grande boundary to El Paso as the international boundary, but the Texas claim to New Mexico, then occupied by United States troops, remained in dispute. Texas decreed a county, Santa Fe County, to include the area, but the people of New Mexico protested the Texas claim. After prolonged debate in Congress and the Texas newspapers and near-armed dispute, an adjustment was reached in the Compromise of 1850. The compromise line ran the Texas western boundary from El Paso east along the thirty-second parallel to the 103d meridian, up that meridian to 36°30" latitude, and along that line to the 100th meridian, thence down the 100th meridian to the Red River. The thirty-six-thirty line was chosen since Texas was a slave state and that line had been established in 1820 as the Missouri Compromise line between slave and free territory in the Louisiana Purchase. After 1850 the line was apparently fixed, but the boundary was not. An error in the surveying of the western line gave Texas a strip about two miles wide west of the 103d meridian; Congress confirmed the boundary, as surveyed, in a joint resolution of February 16, 1911. Shifts in the channel of the Rio Grande necessitated other changes. In 1929 the Supreme Court assigned to Texas 25,000 acres of former New Mexican land lying on the western side of the channel of the river. The Rio Grande Rectification Project, authorized in 1933, provided for the exchange of 3,500 acres of land, part of it in the El Paso area, between the United States and Mexico. The International Boundary and Water Commission is a permanent agency with jurisdiction over the boundary questions on the Rio Grande.

As defined in the Adams-Onís Treaty of 1819, the northern and northwestern boundary of Texas followed the course of the Red River westward to the 100th meridian and north along that meridian to the Arkansas River, the whole line as depicted in the Melish map of 1818. Then the Compromise of 1850 placed the north line of the Panhandle at 36°30". No problem arose over this boundary until 1858, when A. H. Jones and H. M. Brown, who had been employed to locate the 100th meridian in making surveys of grants to various Indian tribes, discovered that the Melish map had erroneously located that meridian 100 miles too far east. In 1852 Randolph B. Marcy discovered that there were two main branches of the Red River lying between the Melish line and the 100th meridian. The supposedly correct meridian was surveyed in 1860, the same year that the Texas legislature decreed Greer County. Because of the Civil War and Reconstruction, Greer County was not organized until 1886 and was in process of being settled when the United States land commissioner protested the Texas claim to the land north of the Prairie Dog Town Fork of the Red River. The controversy went to the United States Supreme Court, which ruled on March 16, 1896, that the Texas boundary was the south or Prairie Dog Town Fork of the Red River and the astronomical 100th meridian.

The northern boundary again became controversial in 1919, when Texas drillers discovered oil in the bed of the Red River just north of Burkburnett. Oklahoma claimed the bed of the river and sued Texas for title in the Supreme Court. The Greer County case had defined the Texas boundary as the south bank of the Red River, but Texas claimed that the south bank in 1919 was not the same as the south bank at the time of the Melish map and the treaty of 1819. The contest became a three-cornered suit, with Oklahoma claiming the entire riverbed, Texas claiming title to the south half, and the United States disputing both claims and asserting ownership of the south half as trustee for the Indians. The decision in the four-year suit was rendered on January 15, 1923. In it the Supreme Court defined a riverbank as the bank cut by the normal flow of water, or where vegetation stopped, gave Oklahoma the north half of the bed and political control of the entire bed, and gave the United States the south half of the bed as trustee for the Indians, but allowed Texas to retain control of the oil wells in the floodplain between the riverbanks. To prevent further dispute, the court ordered a survey of the south bank as it was in 1819 and the placing of concrete markers along the survey line. The report of Arthur Kidder and Arthur H. Stiles, the commissioners who made the survey, was accepted on April 25, 1927.

In the meantime, in 1920 Texas sued Oklahoma on the grounds that the surveys of the 100th meridian made in 1858 and 1860 had erroneously placed that meridian a half mile too far west. Surveys made in 1892 and 1902 had not solved the problem of ownership of an area 134 miles long and between 3,600 and 3,700 feet wide. One Oklahoma resident complained that she had not moved a foot in forty-five years but had lived in one territory, two states, and three counties. In 1927 the Supreme Court ordered Samuel S. Gannett to survey the meridian. He worked from 1927 to 1929, largely at night to avoid the aberrations of heat waves, and placed concrete markers at every two-thirds of a mile. The court ruled in 1930 that the Gannett line was the true meridian. Oklahoma tried unsuccessfully to buy back the strip that the Texas legislature incorporated in 1931 in Lipscomb, Hemphill, Wheeler, Childress, and Collingsworth counties. Higgins was the only town in the ceded area. See also NECHES RIVER BOUNDARY CLAIM, TREATIES OF VELASCO.

Bunyan H. Andrew, "Some Queries Concerning the Texas-Louisiana Sabine Boundary," Southwestern Historical Quarterly 53 (July 1949). Jacqueline Eckert, International Law and United States-Mexican Boundary Relations (Ph.D. Thesis, University of Texas, 1939). Grant Foreman, "Red River and the Spanish Boundary in the Supreme Court," Chronicles of Oklahoma 2 (March 1924). Herbert P. Gambrell and Lewis W. Newton, A Social and Political History of Texas (Dallas: Southwest Press, 1932). Charles W. Hackett, ed., Pichardo's Treatise on the Limits of Louisiana and Texas (4 vols., Austin: University of Texas Press, 1931–46). J. Evetts Haley, The XIT Ranch of Texas and the Early Days of the Llano Estacado (Chicago: Lakeside, 1929; rpts., Norman: University of Oklahoma Press, 1953, 1967). Webb L. Moore, The Greer County Question (San Marcos, Texas: Press of the San Marcos Record, 1939).


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Time Periods:

  • Antebellum Texas

The following, adapted from the Chicago Manual of Style, 15th edition, is the preferred citation for this entry.

Anonymous, “Boundaries,” Handbook of Texas Online, accessed September 28, 2020,

Published by the Texas State Historical Association.