Sabine River (Texas–Louisiana) in the context of "Adams–Onís Treaty"

Florida (/ˈflɒrɪdə/ FLORR-ih-də; Spanish: [floˈɾiða] ) is a state in the Southeastern and South Atlanticregions of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia to the north, the Atlantic Ocean to the east, the Straits of Florida to the south, and The Bahamas to the southeast. About two-thirds of Florida occupies a peninsula between the Gulf of Mexico and the Atlantic Ocean. It has the longest coastline in the contiguous United States, spanning approximately 1,350 miles (2,170 km), not including its many barrier islands. It is the only state that borders both the Gulf of Mexico and the Atlantic Ocean. With a population of over 23 million, it is the third-most populous state in the United States and ranks seventh in population density as of 2020. Florida spans 65,758 square miles (170,310 km), ranking 22nd in area among the states. The Miami metropolitan area, anchored by the cities of Miami, Fort Lauderdale, and West Palm Beach, is the state's largest metropolitan area, with a population of 6.138 million; the most populous city is Jacksonville. Florida's other major population centers include Tampa Bay, Orlando, Cape Coral, and the state capital of Tallahassee.

Various Native American groups have inhabited Florida for at least 14,000 years. In 1513, Spanish explorer Juan Ponce de León became the first documented European to make landfall in the region and named it La Florida (Spanish for "land of flowers"; [la floˈɾiða]), giving the territory its present name. Spain subsequently incorporated Florida into the Spanish Empire in the early 16th century. In 1565, it founded St. Augustine, the oldest continuously inhabited European-established settlement in the continental United States. The region was frequently coveted and attacked by Great Britain throughout the 18th century. Britain briefly gained control of Florida in 1763, but Spain recovered it in 1783 following the British defeat in the American Revolutionary War. Florida remained under Spanish rule until it was ceded to the United States in 1821, in exchange for U.S. recognition of Spanish sovereignty in Texas and the resolution of the border dispute along the Sabine River. Florida was admitted as the 27th state on March 3, 1845, and was the principal location of the Seminole Wars (1816–1858), the longest and most extensive of the American Indian Wars. The state seceded from the Union on January 10, 1861, becoming one of the seven original Confederate States, and was readmitted to the Union after the Civil War on June 25, 1868.

The Seminole Wars (also known as the Florida Wars) were a series of three military conflicts between the United States and the Seminoles that took place in Florida between about 1816 and 1858. The Seminoles are a Native American nation which coalesced in northern Florida during the early 1700s, when the territory was still a Spanish colonial possession. Tensions grew between the Seminoles and American settlers in the newly independent United States in the early 1800s, mainly because enslaved people regularly fled from Georgia into Spanish Florida, prompting slaveowners to conduct slave raids across the border. What began as small cross-border skirmishes became the First Seminole War, as Andrew Jackson led U.S. forces into Florida—despite Spanish objections—to pursue the Seminoles. Jackson's forces destroyed several Seminole, Mikasuki and Black Seminole towns, as well as captured Fort San Marcos and briefly occupied Pensacola before withdrawing in 1818. In 1819 the U.S. and Spain agreed to transfer Florida in the Adams–Onís Treaty; in return, the United States renounced its claims to Texas and fixed the boundary at the Sabine River.

The United States gained possession of Florida in 1821 and coerced the Seminoles into leaving their lands in the Florida panhandle for a large Indian reservation in the center of the peninsula per the Treaty of Moultrie Creek. In 1832 by the Treaty of Payne's Landing, however, the federal government under United States President Andrew Jackson demanded that they leave Florida altogether and relocate to Indian Territory (modern day Oklahoma) as per the Indian Removal Act of 1830. Those who refused to move resisted violently, leading to the Second Seminole War (1835–1842), which was by far the longest and most wide-ranging of the three conflicts. Initially, less than 2,000 Seminole warriors employed hit-and-run guerilla warfare tactics and knowledge of the land to evade and frustrate a combined U.S. Army and Marine force that grew to over 30,000. Instead of continuing to pursue these small bands, American commanders eventually changed their strategy and focused on seeking out and destroying hidden Seminole villages and crops, putting increasing pressure on resisters to surrender or starve with their families.

Kilgore (/ˈkɪlɡɔːr/ ) is a city in the Gregg and Rusk counties in Texas, United States. As of the 2020 census, its population was 13,376. It is located where Interstate 20 and US 259 converge south of the Sabine River.

The U.S. state of Texas has a series of estuaries along its coast on the Gulf of Mexico, most of them bounded by the Texas barrier islands. Estuaries are coastal bodies of water in which freshwater from rivers mixes with saltwater from the sea. Twenty-one drainage basins terminate along the Texas coastline, forming a chain of seven major and five minor estuaries: listed from southwest to northeast, these are the Rio Grande Estuary, Laguna Madre, the Nueces Estuary (Corpus Christi Bay), the Mission–Aransas Estuary (Aransas Bay), the Guadalupe Estuary (San Antonio Bay), the Colorado–Lavaca Estuary (Matagorda Bay), East Matagorda Bay, the San Bernard River and Cedar Lakes Estuary, the Brazos River Estuary, Christmas Bay, the Trinity–San Jacinto Estuary (Galveston Bay), and the Sabine–Neches Estuary (Sabine Lake). Each estuary is named for its one or two chief contributing rivers, excepting Laguna Madre, East Matagorda Bay, and Christmas Bay, which have no major river sources. The estuaries are also sometimes referred to by the names of their respective primary or central water bodies, though each also includes smaller secondary bays, inlets, or other marginal water bodies.

These water bodies include some of the largest and most ecologically productive coastal estuaries in the United States and contribute significantly to the ecological and economic resources of Texas. They are included in a number of national protected areas such as National Wildlife Refuges, a National Seashore, and a National Estuarine Research Reserve, as well as various state parks and other regional protected areas. The two most economically important (the Nueces and Trinity–San Jacinto Estuaries) have been designated by the United States Environmental Protection Agency as estuaries of national significance under the National Estuary Program. The Gulf Intracoastal Waterway runs through each of the major estuaries, linking Texas ports with others along the Gulf Coast of the United States.

Big Sandy is a town in Upshur County, Texas, United States. As of the 2020 census, the town's population was 1,231. A lake of the same name is cut nearly in half by U.S. Highway 80, the main thoroughfare of Big Sandy. It lies directly west of the larger cities of Gladewater and Longview.

The Sabine River flows just south of Big Sandy. In the 19th century, Walters' Bluff Ferry operated on the Sabine, with passage across costing 40 cents per person and up to 75 cents for wagons.