Historic county of England
Hertfordshire
Chiltern edge west, Lea and Colne valleys south, rolling chalk country north.
Hertfordshire lies immediately north of London but retains a strong identity as a county of river valleys, chalk uplands and market-town country. Hertford stands on the Lea system in the east; St Albans occupies higher ground above the Ver; Watford belongs to the Colne corridor; and the north opens into more rural chalk and clay landscapes.
The Chilterns reach into the west, while the Lea, Colne and their tributaries lead south towards the Thames basin. Modern towns, railways and suburban growth have intensified these corridors, but did not create them. Hertfordshire is best understood as a series of valleys and routes descending from higher country towards London.
- River crossing & market site
- Earliest reference: Anglo-Saxon Chronicle
- London’s hinterland
- Area: 633 sq miles / 1,639 sq km
- Population: 1,157,166
- County Top: Pavis Wood (800ft / 244m)
County geography
Current Census
Contemporary Census profile
England and Wales Census 2021. Detailed contemporary statistics are available in the Geographic County Census Explorer.
- Population density
- 1,959.0 people per sq mi (756.4 people per km²)
- Population
- 1,240,679
Valleys towards London
The Lea and Colne systems provided natural routes through Hertfordshire centuries before modern roads and railways. Settlements repeatedly developed where rivers, crossing points and higher ground met.
Those same corridors later attracted canals, railways and urban growth, giving Hertfordshire a particularly clear relationship between physical and human geography.
Chalk, Chiltern and woodland
Western and northern Hertfordshire rise onto chalk country associated with the Chilterns. Beechwoods, dry valleys and steeper ridges contrast with the lower clay and river country further south and east.
Although Hertfordshire is densely settled in places, extensive farmland and woodland survive surprisingly close to its towns.
Old routes, new towns
Twentieth-century garden cities, new towns and commuter growth transformed the appearance of parts of Hertfordshire. Yet their position continued an older pattern: movement north from London was already channelled by valleys, ridges and established road corridors.
Modern development therefore sits over a much older county structure.
County questions
Questions about Hertfordshire
Do places reached by the London conurbation stop being in Hertfordshire?
No. Urban growth and later administrative boundaries do not alter the underlying geographic county.
Why does Hertfordshire have so many commuter towns?
Its proximity to London matters, but so does its physical geography. Long-established corridors through river valleys and across chalk country made north–south movement unusually easy.
County record
Names and continuity
- Formal name
- County of Hertford
- Foundation
- c. 1011
Hertfordshire and County of Hertford are forms of the same county name. Hertford gave the shire its name, which is recorded in the Anglo-Saxon Chronicle before the Norman Conquest.