4.1 - Economic sectors, location and change

Classifying economic work

An economic activity produces a good or provides a service. We classify the work being done, rather than assuming everyone in the same place does the same kind of work.

A fish caught at sea is a primary output. Processing and canning it is secondary activity; transporting and selling it are tertiary. Research into a new preservation method is quaternary. These activities depend on one another: a factory still needs raw materials, distribution and knowledge.

Employment structure is the distribution of workers among sectors. It differs from the distribution of output or income. A highly productive factory may produce a large value of goods with relatively few workers. Many statistical sources include quaternary work within tertiary services; check categories before comparing them.

The Clark Fisher model

The Clark Fisher model describes a common long-term change from a primary-dominated employment structure towards manufacturing and then services. It describes broad tendencies; it is not a rule that every country must follow at the same speed.

Where productivity is low, growing enough food can require a large agricultural workforce. Mechanisation, better transport and farming knowledge can increase output per worker. Fewer workers are then needed to produce a given harvest, while industrial investment creates factory jobs. Rising household incomes increase demand for manufactured goods, encouraging secondary employment.

Later, automation can also reduce the workers needed in manufacturing. Some production moves to other countries. Meanwhile, higher incomes, longer education and an ageing population increase demand for services such as leisure, finance, schools and healthcare. Research and information work can grow where skilled workers, universities and digital networks support it.

These changes do not mean farming becomes unnecessary or factories disappear. A sector's share can fall while its actual employment rises. If manufacturing employment increases from 2 million to 3 million but total employment doubles from 10 million to 20 million, manufacturing's share falls from 20% to 15%. Its employment grew; other sectors grew faster.

The model simplifies countries with different histories, policies and resource endowments. An oil exporter, a tourism-dependent island and an economy exporting software may have very different structures at similar development levels. Informal work and differences in statistical classification can also be hidden.

Why economic activities locate where they do

A business chooses a location by balancing access, costs, risks and the requirements of its activity. The cheapest land is not automatically the best site if customers or supplies cannot reach it.

Primary activities are strongly tied to resources: mining requires a deposit, farming needs suitable land and water, and fishing depends on marine resources. Access still matters because heavy or perishable products must reach processing plants and markets. Depletion can close a mine even where workers and roads remain.

Secondary businesses may need raw materials, reliable energy, water, land, transport and labour. A steelworks can benefit from a port that imports heavy inputs. An electronics assembler may place more weight on dependable supply chains, skilled workers and rapid distribution. A large market can reduce delivery costs and encourage nearby suppliers, creating an industrial cluster.

Tertiary activities differ too. A convenience shop needs nearby customers and visible access, while a hospital needs a reachable catchment and suitable facilities. A distribution warehouse may prefer a motorway junction on cheaper peripheral land. Quaternary firms often value universities, specialist workers, research partners, high-speed connections and an attractive environment that helps recruit staff.