Silver, the mining camps and the road

Silver was found at Zacatecas in 1546. Two years later, in 1548, the mother lode at Guanajuato was struck. Those two dates explain the map of the Bajío better than any subsequent development plan.

The logistical problem of a mine

A silver mine on the dry northern plateau cannot feed itself. There is not enough agriculture, no livestock, no workshops. Everything — grain, meat, leather, salt, mercury, timber, mules — has to arrive from somewhere else, and the silver has to leave by the same road.

That road was the Camino Real de Tierra Adentro, running north from Mexico City through Querétaro and Celaya and on toward Guanajuato and Zacatecas. The Bajío sat exactly in the middle: close enough to the mines to supply them, fertile enough to produce the supply.

So the Bajío's agricultural economy was neither earlier than mining nor independent of it. It was its consequence. The grain haciendas existed because there were mining cities to feed.

Camps, presidios and missions

The road crossed Chichimeca territory and was contested for decades. The crown answered with a chain of presidios and settlements along the route, serving military and supply functions at once. Many towns on the corridor have that origin: they were founded not where the soil was best but where the road needed a stop.

The missions are a separate and later chapter. Those of the Sierra Gorda in Querétaro, built in the mid-eighteenth century, sit in the mountains — off the plain and off the main silver route. It is worth not conflating the two geographies: the corridor is an axis of mining logistics; the sierra is something else.

La Valenciana and the problem with the figures

The Valenciana mine at Guanajuato reached peak production between 1768 and 1804. It was one of the most productive silver mines in history. Exactly how productive is where the sources stop agreeing.

Verification note

At least four versions of La Valenciana's share of world silver production are in circulation: two-thirds of the world total, two-thirds of New Spain's total, 60% of eighteenth-century world output, and 20% of the world across 250 years. These figures are mutually incompatible, and the highest of them appear mainly in tourism promotion material.

We publish no preferred figure here. What is unambiguously verifiable is that Guanajuato was among the most important silver districts in the world in the late eighteenth century, alongside Zacatecas, Potosí and Ouro Preto. Anyone who needs the exact number should go to the Real Hacienda accounts, not to an article — including this one.

Production stopped in 1810 with the war of independence. In 1817 Xavier Mina ordered the machinery burned. The mines flooded. Recovery took decades and never returned to the earlier scale.

What remained

Silver ceased to be the dominant business two centuries ago. The geometry it left did not.

The corridor's urban network — León, Silao, Irapuato, Salamanca, Celaya, Querétaro — consolidated along the line of the silver road
Federal Highway 45 roughly follows that axis, and the 45D toll road doubles it
The 30-to-50-kilometre spacing between cities corresponds to mule-train days, not modern planning
Guanajuato city, by contrast, ended up outside the industrial corridor: it is in the mountains, where the vein was, not on the plain

That last observation has practical consequences. The state capital is not its economic or logistical centre, and has not been since the business stopped being extractive. Anyone planning corridor operations who takes the capital as their reference point is working from a 1780 map.