Louisiana Geography

The state is bordered to the west by the state of Texas; to the north by Arkansas; to the east by the state of Mississippi; and to the south by the Gulf of Mexico.

The surface of the state may properly be divided into two parts, the uplands, and the alluvial, coast and swamp regions. The alluvial regions, including the low swamps and coast lands, cover an area of about 20,000 square miles (52,000 km²); they lie principally along the Mississippi River, which traverses the state from north to south for a distance of about 600 miles (1,000 km) and ultimately emptying into the Gulf of Mexico, the Red River, the Ouachita River and its branches, and other minor streams. The breadth of the alluvial region along the Mississippi is from 10 to 60 miles (15 to 100 km), and along the other streams it averages about 10 miles (15 km). The Mississippi flows upon a ridge formed by its own deposits, from which the lands incline toward the low swamps beyond at an average fall of six feet per mile (3 m/km). The alluvial lands along other streams present very similar features. These alluvial lands are never inundated, save when breaks occur in the levees by which they are protected against the floods of the Mississippi and its tributaries. These floods, however, do not occur annually, and they may be said to be exceptional. With the maintenance of strong levees, these alluvial lands would enjoy perpetual immunity from inundation.

The uplands and contiguous hill lands of the north and northwestern part of the state have an area of more than 25,000 square miles (65,000 km²), and they consist of prairie and woodlands. The elevations above sea-level range from 10 feet (3 m) at the coast and swamp lands to 50 and 60 feet (15–18 m) at the prairie and alluvial lands. In the uplands and hills the elevations rise to Driskill Mountain the highest point in the state at only 535 feet (163 m) above sea level. Only two other states in the union, Florida and Delaware, are geographically lower than Louisiana, though several other states, such as Kansas and Nebraska, are geographically flatter.

Besides the navigable rivers already named (some of which are called bayous), there are the Sabine, forming the western boundary, and the Pearl, the eastern boundary, the Calcasieu, the Mermentau, the Vermilion, the Teche, the Atchafalaya, the Boeuf, the Lafourche, the Courtableau, the D'Arbonne, the Macon, the Tensas, the Amite, the Tchefuncte, the Tickfaw, the Natalbany, and a number of other streams of lesser note, constituting a natural system of navigable waterways, aggregating over 4,000 miles in length, which is unequalled in the United States. The state also has 1,060 square miles (2,745 km²) of land-locked bays, 1,700 square miles (4,400 km²) of inland lakes, and a river surface of over 500 square miles (1,300 km²).

Louisiana has a humid subtropical climate (Koppen climate classification Cfa), perhaps the most "classic" example of a humid subtropical climate of all the Southeastern states, with long, hot, humid summers and short, mild winters. The subtropical characteristics of the state are due in large part to the influence of the Gulf of Mexico, which even at its farthest point is no more than 200 miles (320 km) away. Precipitation is frequent throughout the year, although the summer is slightly wetter than the rest of the year, and there is a dip in precipitation in October, with Southern Louisiana receiving far more, copious rainfall, especially during the winter months. Summers in Louisiana are hot and humid with high temperatures from mid-June to mid-September averaging 90°F (32°C) or more and overnight lows averaging above 70°F (22°C). In the summer, the extreme maximum temperature is much warmer in the north than in the south, with temperatures near the Gulf of Mexico occasionally reaching 100°F (38°C), although temperatures above 95°F (35 °C) are commonplace. In northern Louisiana, temperatures frequently reach above 105°F (41°C) in the summer. Temperatures are generally mildly warm in the winter in the southern part of the state, with highs around New Orleans, Baton Rouge, the rest of south Louisiana, and the Gulf of Mexico averaging 66°F (19°C), while the northern part of the state is mildly cool in the winter with highs averaging 59°F (15°C). The overnight lows in the winter average well above freezing throughout the state, with 46°F (8°C) the average near the Gulf and an average low of 37°F (3°C) in the winter in the northern part of the state. Louisiana does have its share of cold fronts which frequently drop the temperatures below 20°F (-8°C) in the northern part of the state, but almost never do so in the southern part of the state. Snow is not very common near the Gulf of Mexico, although those in the northern parts of the state can expect one to three dustings per year, with the frequencey increasing northwards.

Louisiana is often affected by tropical cyclones and is very vulnerable to strikes by major hurricanes, particularly the lowlands around and in the New Orleans area. The unique geography of the region with the many bayous, marshes and inlets can make major hurricanes especially destructive. The area is also prone to frequent thunderstorms, especially in the summer. The entire state averages over 60 days of thunderstorms a year averaging more thunderstorms than any other state except Florida. Louisiana averages 27 tornadoes annually, and the entire state is vulnerable to a tornado strike, with the extreme southern portion of the state slightly less than the rest of the state. Tornadoes are much more common from January to March in the southern part of the state, and from February through March in the northern part of the state.[5]

• September 24, 2005, Rita (Category 3 at landfall) struck southwestern Louisiana, flooding many parishes and cities along the coast, including, Cameron Parish, Lake Charles, Terrebonne Parish, Houma, and other towns. The storm's winds further weakened the still damaged levees in New Orleans, re-flooding parts of the city.

• August 29, 2005, Katrina (Category 4 at landfall) struck and devastated southeastern Louisiana, while damaged levees in New Orleans allowed parts of the city to flood. The city was virtually closed until October. It is estimated that more than two million people in the Gulf region were displaced by the hurricane, with more than 1,500 fatalities in Louisiana alone. Public outcry criticized the government at the local, state, and federal levels, citing that the response was neither fast nor adequate. The hurricane and the challenge to protect wetlands are featured in the documentary film Hurricane on the Bayou.

• August 1992, Andrew (Category 3 at landfall) struck south-central Louisiana, killing 4 people, knocking out power to nearly 150,000 citizens and destroying hundreds of millions of dollars of crops in the state.

• September 9, 1965, Betsy (Category 3 at landfall) came ashore in Louisiana causing massive destruction, being the first hurricane in history to cause one billion dollars in damage (over ten billion in inflation-adjusted USD). The storm hit New Orleans particularly hard by flooding approximately 35% of the city (including the Lower 9th Ward, Gentilly, and parts of Mid-City), pushing the death toll in the state to 76.

• August 1969, Camille (Category 5) had a 23.4 ft. storm surge and killed 250 people. Although Camille officially made landfall in Mississippi and the worst impacts were felt there, it effects were still felt in Louisiana. However, New Orleans was spared from the brunt of the storm.

• June 1957, Audrey (Category 4) devastated southwest Louisiana, destroying or severely damaging 60–80 percent of the homes and businesses from Cameron to Grand Chenier. 40,000 people were left homeless and over 300 people were killed in the state.

The underlying strata of the state are of Cretaceous age and are covered by alluvial deposits of Tertiary and post-Tertiary origin. A large part of Louisiana is the creation and product of the Mississippi River. It was originally covered by an arm of the sea, and has been built up by the silt carried down the valley by the great river.

Near the coast, there are many salt domes, where salt is mined and oil is often found.

Owing to the extensive flood control measures along the Mississippi river and to natural subsidence, Louisiana is now suffering the loss of coastal land area. State and federal government efforts to halt or reverse this phenomenon are under way; others are being sought. There is one bright spot, however, the Atchafalaya River is creating new delta land in the South-Central portion of the state.

Louisiana contains a number of areas which are, in varying degrees, protected from human intervention. In addition to several stations of the National Park Service, and a federally recognized national forest, Louisiana itself operates, among other programs, a system of state parks and recreation areas throughout the state. Administered by the Louisiana Department of Wildlife and Fisheries, the Louisiana Natural and Scenic Rivers System provides a degree of protection for 48 rivers, streams and bayous in the state.

National Park Service Areas under the management and protection of the National Park Service include:

• Cane River National Heritage Area near Natchitoches
• Cane River Creole National Historical Park near Natchitoches, Louisiana.
• Jean Lafitte National Historical Park and Preserve, headquartered in New Orleans, with units in St. Bernard Parish, Baritaria (Crown Point), and Acadiana (Lafayette)
• New Orleans Jazz National Historical Park
• Poverty Point National Monument at Epps, Louisiana.
• Saline Bayou, a national wild and scenic river in northern Louisiana.

National Forest

• Kisatchie National Forest is Louisiana's only national forest.

State parks and recreational areas Louisiana operates a system of 19 state parks, 16 state historic sites and one state preservation area.

Map of Louisiana