Direct Contiguity (v3.2)

Overview 

Version 3.2 of the COW Direct Contiguity data identifies all direct contiguity relationships between states in the international system from 1816 through 2016. The classification system for contiguous dyads is comprised of five categories, one for land contiguity and four for water contiguity. Land contiguity is defined as the intersection of the homeland territory of the two states in the dyad, either through a land boundary or a river (such as the Rio Grande in the case of the US-Mexico border). Water contiguity is divided into four categories, based on a separation by water of 12, 24, 150, and 400 miles.

Citation 

In any papers or publications that utilize this data set, users are asked to give the version number and cite the article of record for the data set, as follows:

Correlates of War Project. Direct Contiguity Data, 1816-2016. Version 3.2. 

Users are asked to cite the current article of record for the data set, as follows:

Stinnett, Douglas M., Jaroslav Tir, Philip Schafer, Paul F. Diehl, and Charles Gochman. 2002. "The Correlates of War Project Direct Contiguity Data, Version 3." Conflict Management and Peace Science 19(2):58-66.

Additional details of the basic coding process were elaborated in:

Charles S. Gochman, 1991, "Interstate Metrics: Conceptualizing, Operationalizing, and Measuring the Geographic Proximity of States since the Congress of Vienna," International Interactions 17(1): 93-112. 

Data Generating Procedures 

Excerpts from the article of record:

The classification system for contiguity is comprised of five categories, one for land contiguity and four for water contiguity. Land contiguity is defined as the intersection of the homeland territory of the two states in the dyad, either through a land boundary or a river (such as the Rio Grande along the US-Mexico border). Water contiguity is based on whether a straight line of no more than a certain distance can be drawn between a point on the border of one state, across open water (uninterrupted by the territory of a third state), to the closest point on the homeland territory of another state. Four different levels of water contiguity are recorded, based on the distance between the two states' territories: up to 12 miles (reflecting the widely recognized 12-mile limit for territorial waters), 24 miles (reflecting the maximum distance at which two states' 12-mile territorial limits can intersect), 150 miles (from the original 1816-1965 version of the data set, reflecting what was considered the average distance that a sailing ship could travel in one day), and 400 miles (the maximum distance at which two 200-mile exclusive economic zones can intersect).

The coding for each dyad is always the closest form of contiguity for that year. Thus, if a dyad shares a land border and is also separated by a stretch of water less than 400 miles, that dyad will be coded based on the closest form of contiguity (the land border). If the type of contiguity for a dyad changes during a given year, only the closest classification is recorded for that year, in order to prevent multiple records for one dyad-year from appearing in the data set.

A variety of sources have been used in the process of collecting these data. The sources used for earlier versions of the data are identified in Gochman (1991); more recent updates have relied on various editions of the Times Atlas of the World, National Geographic Atlas of the World, Hammond World Atlas, and Oxford Atlas of the World.

Full details on changes made in the data for v3.2 are included in the codebook that is downloaded with the data files.

Data Set 

All files pertaining to this data set are to be found in the file "DirectContiguity320.zip." This data set may be downloaded below. This downloadable data archive includes a text file with full codebook, as well as three data files that are provided in .csv and .dta format, which can easily be read into any spreadsheet or statistical software. The six data files are:

• contdir.csv: The master data file (with one entry per contiguity relationship)
• contdir.dta: .dta format of the master data file 
• contdird.csv: A directed dyad-year-level version of the master data
• contdird.dta: dta format of the directed dyad-year data
• contdirs.csv: A state-year-level data set calculated from the master data
• contdirs.dta: dta format of the state-year data

• Direct Contiguity Codebook.pdf: The codebook for Version 3.2 for the Direct Contiguity data.

Questions and Feedback 

The contiguity data sets are hosted by Paul Hensel, University of North Texas, under the COW Data Hosting Program. In case of questions or concerns concerning the data or coding rules, he may be contacted by email at phensel@unt.edu.