As the urbanization of sister cities, such as El Paso and Ciudad Juarez, is extremely interesting – starting with their singular origin to their development as two seprate cities, to their socio-cultural, economic and even political interdependencies, I will focus quite a bit on history in the next couple of posts.
To begin, a bit of urban history through a common past: El Paso del Norte
From 1521 to 1810, Spain imposed a rigid administrative system on the Mexican provinces. King Phillip II developed a comprehensive guide of ordinances to aid colonists in locating, building, and populating settlements. The ordinances, titled the Laws of the Indies, where guided and regularized the establishment of presidios (military supervision guard against hostilities) missions (foothold of ecclesiastic conversion of Indians to keep them under ecclesiastical authority), and pueblos or villas (civilian towns under the authority of an ayuntamiento or town council). They codified the city planning process and represented some of the first attempts at a general plan. The design consisted in a grid-pattern where streets were oriented in a cardinal direction and radiated from a main plaza. The urban morphology developed around the religious and civic nucleus of a central plaza. As distances increased from the plaza, there was a decline of socio-economic status.
[This is quite different from the Portuguese Colonial development - for example, that of Sao Paulo]
These ordinances also resulted in the segregation of Indians into the disorganized clusters or shabby dwellings on the outskirts of town. As such new towns were composed of an urbanized part where the civilized lived, and another with those dominated social groups deemed inferior. We can make a parallel observation with the current social segregation seen in the majority of Latin American cities, where uncontrolled, marginalized settlements dominate the peripheral space in most Latin-American cities.
The early settlement of the sister cities of El Paso and Juarez, named Paso del Norte, was first established with the mission of Nuestra Señora de Guadalupe founded in 1656. This was as strategic settlement for the Spaniards as its location, where the Rio Grande meets the Franklyn Mountains, created a gateway to upriver settlements in present New Mexico and could easily benefit from the travel and trade.
The main construct of the town was a colonial core, with a typical grid-pattern, cutting straight up the steep slopes of the Franklyn Mountains, oriented northeast of the Rio Grande with settlement extensions along various irrigation canals. The community, sitting on slightly elevated land, overlooks the floodplain of irrigated fields to the East.
When Mexico won its independence from Spain, Mexican officials encouraged more business activity with the United States allowing El Paso del Norte to benefit from an increase in the volume of trade. With the US-Mexico war, the 1848 Treaty of Guadalupe-Hidalgo protracted a series of negotiations between the two nations. The Mexican territories of Alta California and Santa Fé de Nuevo México were ceded to the United States. The treaty decreed that the international border would follow the Rio Grande for nearly 2000 mile (3,138 km or 1,950 miles), therefore cutting the original Paso del Norte town in two halves, and giving birth to the present cities of El Paso and Ciudad Juarez.
Following this post, BORDER STRADDLING :: NEW SHAPING INFLUENCES
 Luckingham, Bradford. The Urban Southwest, a Profile History of Albuquerque-El Paso-Phoenix-Tuscon. P. 5