Last week, I wrote about how kidnappings in Nigeria have soared over the past 30 years. Time trends are important in understanding the context of the recent mass kidnapping of hundreds of Nigerian schoolgirls, but so are geographical trends. One reader asked:

Reader Comment
To answer that question, I went back to the Global Database of Events, Language and Tone (GDELT), our original data source. The 25,247 kidnappings that GDELT has recorded taking place in Nigeria since 1982 seem to have occurred across the country.

Kidnappings in Nigeria, 1982-present

The rapid acceleration in kidnappings in the past decade is obvious, but deciphering regional patterns is harder — especially for those of you who, like me, don't have a detailed knowledge of Nigerian geography. So, I looked at population data and calculated the number of kidnappings per 100,000 residents in each of the country's 37 states.

Kidnapping rate per 100,000 people, 1982-present

This is a somewhat crude calculation. We're counting all geolocated kidnappings in the GDELT database since 1982 and dividing that by each state's current population. Official kidnapping statistics for Nigeria aren't available, and our numbers do provide a good relative picture; we can see where kidnappings in Nigeria are most prevalent.

The kidnapping rate is the highest — 120 for every 100,000 people — in the Federal Capital Territory, which includes Abuja, Nigeria's capital. Three states in the south also stand out (Rivers, Delta and Bayelsa) with unusually high numbers of kidnappings relative to their population size. One possible explanation is the region's oil wealth, otherwise known as the curse of the black gold. The United Nations news service has also highlighted how oil extraction in the south of Nigeria has been accompanied by violence and criminality.

One other state that was well above the median kidnapping rate (of five kidnappings per 100,000 people) was Borno in the northeast. That's where the militant group Boko Haram, which is responsible for the recent mass kidnapping, is based. When we filtered the results to look at the first four months of 2014, Borno had the highest kidnapping rate in Nigeria.

That's important given the reader's question and our attempt to provide context to the mass kidnapping in the headlines.

Girls were taken from the Government Girls Secondary School in Chibok, which is in Borno state. At the substate level, Chibok has rapidly become more vulnerable to kidnappings; GDELT has recorded 649 kidnappings there in the first four months of this year. GDELT recorded one in 2013, and none before that.