Vietnam’s coastal plain stretches 638 miles in a narrow arch from Vinh (in the former Democratic Republic of Vietnam (North Vietnam)) to Phan Thiet (in the former Republic of Vietnam (South Vietnam)). It is bordered on the east by the blue waters of the South China Sea, or what the Vietnamese refer to as the East Sea, and on the west by the imposing mountains of the Central Highlands. In its narrowest reaches in northern Binh Dinh Province, the coastal plain is less than a mile wide.
The coastal plain possesses a diverse number of environments. In Quang Tri Province, which sits south of what had once been the DMZ, gleaming white sand dunes lie just inland from the sea. Here, stunted trees and scrub brush grow out of the poor, sandy soil. Near Quang Tri City, hundreds of grey, rain-streaked burial crypts stand atop the undulating dunes, a testament to the ferociousness of the fighting in this area during the years of the American War.
Further south, near Phan Thiet, the land becomes dry and barren. The coastal plain through this section lies in the rain shadow of the Central Highlands, which means the region doesn’t receive the rainfall necessary for rice cultivation. As a result, the people have turned away from the land and toward the ocean for their livelihood. In the harbor at Phan Thiet, dozens of anchored fishing vessels signify the chief occupation of the inhabitants. The vessels range in size from large ocean-going trawlers to small round reed boats. The size of the boats suggests the type of water fished by their owners. The round lacquered boats, which resemble the bullboats employed by the Mandan on the Upper Missouri in the nineteenth century, are used in shallow inlets, estuaries, and along the ocean fringe. The bigger trawlers fish the deep waters further offshore.
In central Vietnam, the rice paddy country lies immediately west of the South China Sea. Here the countryside is divided into small plots of rice, with each rice paddy bordered by four low paddy dikes. The square rice paddies, with their diked partitions, have made a checkerboard of the landscape. During the Northeast Monsoon, much of the central coastal plain sinks beneath murky floodwaters. The primary means of traveling cross-country during the rainy season is atop the narrow footpaths along the paddy dikes or over the elevated roadways that link one hamlet to another.
In the Mekong Delta, villages stand on the elevated lands next to dredged waterways or atop the high natural bank lines of rivers. But along the coastal plain, settlement patterns are more haphazard. Some villages can be found at the mouths of rivers, some have been built next to shallow estuaries, and others lie astride ancient trails. Unlike in the Mekong Delta, where the number of suitable village sites is restricted by the availability of elevated land, in the coastal plain there are fewer geographical or environmental limitations on the location of villages.
In the 1960s and 1970s, the coastal plain was not as densely populated as the Mekong Delta, but it did have more people than the plateau country of the Central Highlands. In 1970, the average population density in the coastal districts of Binh Dinh Province stood at 520 people per square mile. Another heavily populated coastal district surrounded the imperial city of Hue.
Major urban centers in the coastal plain can be found at Hue, Danang, Qui Nhon, Tuy Hoa, and Nha Trang. These cities serve as market centers for the paddy country on their environs. In the 1960s, Danang was South Vietnam’s second most populous city, second only to Saigon. Prior to the American military build-up in 1965, Danang, Qui Nhon, and Nha Trang represented three of South Vietnam’s busiest ports. After 1965, the U.S. added to the coastal plain’s list of seaports by constructing modern facilities at Cam Ranh Bay and Chu Lai.
During the French colonial era, engineers laid down a railroad the length of the coastal plain, linking Hanoi to Saigon. Colonial Route (RC) 1 paralleled the railroad line. The French also built highways connecting the coastal port cities with interior towns. RC 11 linked Nha Trang to Da Lat via Phan Rang, RC 19 connected Qui Nhon to Pleiku, and RC 9 tied Danang with Laos via Hue and Quang Tri City. The French roads into the interior carried the wealth of the Central Highlands and lowland plains to the coast for export to France. For example, the coffee grown on French-owned plantations around Pleiku travelled down RC 19 to Qui Nhon. Once there, longshoremen packed the coffee on board ocean-going freighters for shipment to the home country or to another colonial possession within the French empire. The French-built system of roads and ports within Vietnam clearly indicated France’s exploitative intent. France’s geographical constructs siphoned the wealth out of Indochina’s interior, moved it to the string of ports on the South China Sea, and then sent it abroad to enrich the French metropole.
A number of east-flowing rivers, which drain down from the Central Highlands, divide the coastal plain. Several of these rivers experience regular flooding along their lower reaches during the Northeast Monsoon, including the Ben Hai, Cua Viet, and Perfume.
The Vietnamese coastal plain is crowded with people, cluttered with hedgerows, rice paddies, dikes, ditches, and tree-shrouded hamlets, and is frequently filled to the brim with monsoonal runoff. During the American War, the natural and built environments of the coastal plain hampered U.S. mobility, limited the killing power of U.S. weaponry, and contributed to the Vietcong’s protracted war strategy.