As Spaniards approached the Rio Grande from the south in the sixteenth century, they viewed two mountain ranges rising out of the desert with a deep chasm between that offered a ford of the river. This site they named El Paso del Norte (the Pass of the North), which became the future location of two border cities - Ciudad Juárez, Chihuahua, Mexico on the south or right bank of the Rio Grande, and El Paso, Texas, on the opposite side of the river. Since the sixteenth century the pass has been a continental crossroads, as the Camino Real del Tierra Adentro, or Royal Road of the Interior, developed through El Paso del Norte as a north-south route and remained a prominent route during the Spanish and Mexican periods.

The El Paso area was inhabited for centuries by various Indian groups before the Spaniards came. The first Europeans in all probability were Álvar Núñez Cabeza de Vaca and his three companions. These survivors of an unsuccessful Spanish expedition to Florida passed through the El Paso area in 1535 or 1536 as part of their eight-year journey through much of present-day Texas and Northern Mexico, though their exact route is debated by historians. Several years later, in 1540-42, an expedition under Francisco Vázquez de Coronado explored an enormous part of what is now the American Southwest. The first party of Spaniards that certainly saw the Pass of the North was the Rodríguez-Sánchez expedition of 1581, marking the beginning of 400 years of history in the El Paso area. This was followed by the Espejo-Beltrán expedition of 1582 and the historic colonizing expedition under Juan de Oñate, who, on April 30, 1598, in a ceremony at a site near that of present San Elizario, took formal possession of the entire territory drained by the Río del Norte (the Rio Grande). This act, called La Toma, or "the claiming," brought Spanish civilization to the Pass of the North and laid the foundations of more than two centuries of Spanish rule over a vast area.

In the late 1650s Fray García founded the mission of Nuestra Señora de Guadalupe on the south bank of the Rio Grande; it still stands in downtown Ciudad Juárez. The Pueblo Indian Revolt of 1680 sent Spanish colonists and Tigua Indians of New Mexico fleeing southward to take refuge in El Paso del Norte, transplanting the names of New Mexico river pueblos, including La Isleta and Socorro, to the El Paso area. On October 12, 1680, midway between the Spanish settlement of Santísimo Sacramento and the Indian settlement of San Antonio, the first Mass in Texas was celebrated at a site near that of present Ysleta, which was placed on what is now the Texas side by the shifting river in 1829; Ysleta thus has a claim to being the oldest town in Texas. By 1682 five settlements had been founded in a chain along the south bank of the Rio Grande.

By the middle of the eighteenth century about 5,000 people lived in the El Paso area-Spaniards, mestizos and Indians-forming the largest complex of population on the Spanish northern frontier. A large dam and a series of acequias (irrigation ditches) encouraged flourishing agriculture. A large number of vineyards produced fine wine and brandy.

During the Civil War most of the El Paso pioneers were overwhelmingly sympathetic to the South. Although Confederate forces occupied Fort Bliss in 1861, the tide began to turn in favor of the Union cause the following year, and in August the Stars and Stripes was raised once again over Fort Bliss. The local Southern sympathizers eventually received presidential pardons, but some battled for years before they recovered their properties.

Most authorities agree that the arrival of the railroads in 1881 and 1882 was the single most significant event in El Paso history, as it transformed a sleepy, dusty little adobe village of several hundred inhabitants into a flourishing frontier community. As El Paso became a western boomtown, it also became "Six Shooter Capital" and "Sin City," where scores of saloons, dance halls, gambling establishments, and houses of prostitution lined the main streets. In the 1890s reform-minded citizens conducted a campaign to curb El Paso's most visible forms of vice and lawlessness, and in 1905 the city finally enacted ordinances closing houses of gambling and prostitution.

After 1900 El Paso began to shed its frontier image and develop as a modern municipality and significant industrial, commercial, and transportation center. Industries have included smelting, agriculture, refineries, and tourism. El Paso saw years of violence during the Mexican Revolution of 1910-1920, when revolutionaries overthrew the Mexican oligarchy. For more than 130 years Fort Bliss has played a significant role in local, national, and international affairs, and the relationship between the city and the post has always been close.

A major characteristic of border-town El Paso is its special relationship with Mexico in general and Ciudad Juárez in particular. Historic developments such as the Taft-Díaz meeting of 1909; the taking of Ciudad Juárez by the revolutionary forces of Francisco I. Madero in 1911; the activities of Francisco (Pancho) Villa, followed by Gen. John J. Pershing's punitive expedition of 1916; the immigration of Mexican families, rich and poor, during and after the Mexican Revolution; the smuggling and bootlegging activities during the Prohibition era; the Chamizal dispute and its settlement in 1964; and the growing interdependence of the two cities-all attest to the unique relationship existing between El Paso and Ciudad Juárez.