Spain's Urban Landscape: Hierarchy, Distribution, and Key Functions

The Spanish Urban System

Cities constitute a system where the urban network plays a leading role in Spain's territorial organization.

1. Demographic Size of Spanish Cities

The demographic size of cities forms one of the bases of the urban hierarchy. The largest demographic urban areas correspond to seven metropolitan areas, each with over half a million people: Madrid, Barcelona, Valencia, Seville, Bilbao, Malaga, and Zaragoza.

Spatial Distribution of Urban Agglomerations

The spatial distribution of urban agglomerations by demographic size is characterized by two key features:

• a) Peninsular Semi-Ring: In the Iberian Peninsula, large cities form a semi-ring along the periphery, surrounding a less urbanized interior space. The center of this space is occupied by the country's largest urban agglomeration (Madrid). Growth in these peripheral areas has shaped significant territorial axes, acting as lines of contact where population and economic activity are concentrated. These axes include:
  • Northern Axis: This axis is discontinuous.
  • Mediterranean Axis: Extending from Girona to Cartagena, this is the most dynamic axis.
  • Andalusian Urban Network: Developed along the double coastline and the Guadalquivir Valley.
  • Ebro Valley Axis: Functions as a communication corridor between the Bay of Biscay and the Mediterranean, with Zaragoza as its main city.
• b) Northeast Concentration: Five of the seven metropolitan clusters with over 500,000 inhabitants are concentrated in the Northeast. This includes the four major poles of economic activity (Madrid, Barcelona, Bilbao, and Valencia), with Zaragoza occupying a strategic crossroads position.

2. Functions of Spanish Cities

The functions performed by cities are another factor determining their position within the urban system. We define these functions as socio-economic activities that cities project outwards. Several types exist:

• a) Primary Cities: Specialization in primary sector activities.
• b) Secondary Cities: Specialization in industry.
• c) Tertiary Cities: Services are the activities that best define the range of a city's influence.

3. Urban Areas of Influence

In terms of external functions, cities are considered central places, defining an "area of influence." Christaller's Central Place Theory classifies sites based on the variety and quality of functions they perform within a hexagonal catchment area. The resulting organized hexagonal mesh is formed by the areas of influence of each central place. When compared with the Spanish case, Christaller's theoretical model shows an acceptable distribution:

• Madrid is the primary central place, and its influence extends throughout Spain.
• On the periphery are the next most influential urban centers: Barcelona, Valencia, Seville, A Coruña, and Bilbao.
• Mid-level cities include Burgos, Zaragoza, Murcia, and Granada.
• Followed by urban centers of minor influence.

4. The Spanish Urban Hierarchy

a) Metropolises

Metropolises are cities at the top of the hierarchy. Their population typically exceeds 250,000, and they offer diverse, specialized functions related to advanced tertiary services and industry.

• National Metropolises: These are the metropolitan areas of Madrid and Barcelona. They possess highly diverse functions, their area of influence extends throughout the country, and they are closely connected to other global metropolises.
• Regional Metropolises: These include the metropolitan areas of Valencia, Seville, Bilbao, Malaga, and Zaragoza. Their population ranges between 500,000 and 1.5 million inhabitants. They provide advanced administrative and business services, have a regional area of influence, and maintain strong relations with other regional metropolises.
• Sub-Metropolises: With populations between 250,000 and 500,000 inhabitants, these cities still possess significant capabilities and some highly specialized services, serving a sub-regional catchment area.

b) Medium-Sized Cities

Most medium-sized cities are provincial capitals. Their population ranges between 50,000 and 250,000 inhabitants, and their functions are primarily tertiary, though less specialized than metropolises.

c) Small Cities

Small cities have populations under 50,000 inhabitants and offer less specialized functions, mainly administrative and commercial.

Urban relationships can be unidirectional or reciprocal.