Map Regression

Map regression basically involves comparing maps drawn up at different dates, to understand changes over time.  Modern and old Ordnance Survey, tithe, inclosure and estate maps can all be used for this purpose. 

Map regression can be used for a number of purposes:

  • To understand and determine those features that have changed and those that have not.
  • To locate features which may be on earlier maps but have vanished from modern maps.
  • To determine the phases of a building, although there can be inaccuracies on maps when recording buildings especially on the earlier types of maps.
  • To identify field and other boundaries, trackways and roads, as well as locating particular features.

How is map regression done?

It is best to start with the most recent map, such as a modern Ordnance Survey map and gradually work back through time comparing the relevant maps.  Map regression is made simpler if all the maps have been reduced or enlarged to the same scale.  Maps can then be overlaid. 

A good starting point is to identify a number of features or structures, which have not changed, as this provides a framework from which to start locating other features and comparing maps.

It may also be useful to trace maps so they can be more easily overlaid.

Written by Sarah Glover, Assistant Project Officer  (June 2006)