Hertfordshire's representation in the British Parliament can be traced back to the thirteenth century, during the reign of King Edward I of England. By 1307 the county had six representatives; two for the entire county, and two each for St Albans and Hertford. Parliament's role changed steadily over the following centuries, from a body that acted in an advisory role to the English monarch, to a legislative body in its own right. However, Hertfordshire's representation within it remained constant for over 500 years.
By the 19th century it became clear that the national constituency boundaries were in need of reform to reflect the rapidly changing demographics of the country. One of Hertford's Members of Parliament immediately prior to the 1885 Redistribution of Seats Act was Arthur Balfour, who later went on to become Prime Minister. The act divided Hertfordshire into the four constituencies of Hertford, Hitchin, St Albans and Watford. Significant reform of British politics continued in the 20th century, and by 1983 Hertfordshire had 11 constituencies. As of the 2010 election, all of Hertfordshire's eleven MPs are Conservatives. The Liberal Democrats finished second in seven constituencies, while Labour finished second in the remaining four.
This map depicts the locations of the major settlements within Hertfordshire. The line surrounding the lighter area shows the county's boundaries. The inner lines show the boundaries of the county's ten areas of local government. Grey areas depict areas of urban development.
According to the United Kingdom Census 2001, thirty settlements in Hertfordshire had a population of at least 5,000. These include Hertford, the county town, Watford, the most populous settlement, and St Alban's, the only city. Three settlements with populations of over 10,000 have been omitted from this map; Bushey, Croxley Green and Abbots Langley are situated to the immediate south, west and north of Watford respectively.