The trend of the reliefs means that the rivers of the Dominican Republic flow mainly in the longitudinal direction, between one chain and another. The development of the Dominican waterways is modest: the largest is the Yaque del Norte, which runs through the Cibao valley from E to W and flows into the Atlantic; on the other hand, the Yuna crosses the eastern end of the same valley in the opposite direction, which flows into the bay of Samaná and which, like the previous one, feeds a dense network of irrigation canals. The main river on the Caribbean side is the Yaque del Sur, which flows into Neiba Bay after crossing the San Juan Valley. Dell ‘ Artibonite, the longest on the island, only the upper part belongs to the Dominican Republic.
Inhabited first by the Taino, the group of aruacos, then by the Caribs, the current Dominican Republic welcomed perhaps 100,000 Indians upon the arrival of the Spaniards, who in a short time exterminated the entire population. The new conquerors, who had found gold and fertile lands in the country, resorted extensively, as later elsewhere, to the mass recruitment of African slaves. When independence was achieved in 1844, blacks and mulattoes they formed 90% of the population, which amounted to only 125,000 individuals, almost the same number as over three hundred years earlier. The second half of the nineteenth century marked a first phase of significant demographic increase (at the end of the century the population was estimated at 600,000 residents), But above all of modification in the ethnic composition of the state due to the continuous regression of the descendants of African slaves, many of the which among other things were moving to neighboring Haiti, and the simultaneous increase of whites. Rather than depend on natural factors, this increase was the result of the precise policy implemented by the Creole elite, which remained the holder of power with independence and which encouraged the immigration of foreign farmers, with special regard for whites (racial policy then accentuated by Rafael Trujillo); today whites are 16% of the population, mulattoes 73% and blacks 11%. In 1920, the year of the first census official, the number of residents did not reach 900,000 units; but later, especially due to the decrease in mortality, the country recorded a considerable demographic increase, so much so that in 1950 the population totaled over 2 million ab. increased to 3 million in 1960. At the latter date, the average annual birth rate was still very close to 50%, an extremely high value and barely balanced by a mortality rate of around 15%. In the following decade, the first dropped by approx. 10 points, but the second almost halved: therefore, the natural balance remained at 3%, falling to 2.5% in the second half of the 1970s and to 2.1% at the end of the 1980s.
According to itypetravel, the annual growth of population then underwent a progressive decline, settling in the period 2005-2010 around 1.4%; migratory. The Dominican Republic is in fact affected by currents in both directions: emigration is directed especially towards North America and the Dominicans present in the United States are estimated at one million units, while the country is the destination of thousands of migrants coming mainly from other Caribbean islands. Haitian immigrants, in particular, represent the poorest and most discriminated component of the population; in 2004, a national law ordered the expulsion of about 800,000 people from Haiti who entered the country illegally. The most densely settled areas are the Cibao valley, where for example the province of Salcedo reaches 216 residents / km² (the country average is 202 residents / km²), and the southern coastal plain, especially around La Romana (376 residents / km²), in San Cristóbal (459 residents / km²) and to the capital (1824 residents / km² the Distrito Nacional). At the beginning of the 21st century, the trend of internal migratory movements is oriented precisely towards the Caribbean areas, thus overturning the settlement center of gravity, previously represented by the Cibao valley. The presence of Santo Domingo played a decisive role in this process, which marked the rapid urbanization of the population: while in 1950, 72% of it still lived in rural areas, today the relationship has almost reversed and the percentage of the population urban is 70.3%. The capital, from which the name of the state derives, clearly stands out both for the mass of residents (2,688,781 in 2010, with a high annual growth rate), and for the many industrial and commercial activities. Even historically Santo Domingo had a considerable importance which was recognized in 1990 by UNESCO by placing it in the list of world heritage sites. It follows in importance Santiago de los Caballeros (591.985 residents In 2010), located in the Cibao valley and a large center for the processing of tobacco, which is exported from the nearby seaport of Puerto Plata (San Felipe de Puerto Plata); for the rest they are cities of much lesser importance, of which few reach 100,000 residents, and among which we must mention the large agricultural markets of San Francisco de Macorís, located at the foot of the Cordillera Septentrional a short distance from Santiago de los Caballeros, and of San Juan de la Maguana, in the fertile valley of San Juan, as well as the maritime ports of San Pedro de Macorís and La Romana, mainly used for the export of sugar and bananas.