Death March Tracking the casualties of Syria's civil war has been difficult, if not impossible, from the very start. Since March 2011, the United Nations has struggled to glean reliable information from the fog of war. The U.N. has relied on the Human Rights Data Analysis Group (HRDAG), a San Francisco-based non-profit "that applies rigorous science to the analysis of human rights violations around the world," to sort through data from eight different sources including independent observatories and Syrian human rights watchers. Read Tina Rosenberg's fascinating profile of Patrick Ball and the methodology behind HRDAG's numbers, written back when the body count in Syria was estimated at less than 10,000. Killings were counted only if the name of the victim and the date and location of death were known, making the figures provided by the United Nations and HRDAG non-exhaustive; rather, they are the minimum number of people who have died in Syria. Last week, the United Nations said it would no longer be updating its casualty figures. "It was always a very difficult figure," a U.N. spokesman told the Associated Press. It was always very close to the edge in terms of how much we could guarantee the source material was accurate. And it reached a point where we felt we could no longer cross that line. So for the time being, we're not updating those figures. The last time the United Nations announced casualty figures for the Syrian civil war was when the tally surpassed the 100,000 death threshold in July 2013. The lack of access for reporters and humanitarian agencies within Syria has only made this task more difficult. Whether an authoritative tally of casualties in Syria will ever be possible remains an open question, but one thing is clear: over the past three years, the violence has spread dramatically. From the early hotbeds of resistance in Hama and Homs, to the political and cultural hubs of Damascus and Aleppo, to the Syrian borderlands and the Kurdish northeast, the war has metastasized. This map illustrates what that toll looks like across space and time. It visualizes the approximately 74,000 people who died from March 2011 to November 2013. Every flare represents the death of one or more people, the most common causes being shooting, shelling, and field execution. The brighter a flare is, the more people died in that specific time and place. The data used are drawn from the Violations Documentation Center (VDC), the documentation arm of the Local Coordination Committees in Syria which has been one of the eight sources on which HRDAG has based its count. In a June 2013 report, HRDAG cited VDC as the most thorough accounting of casualties in Syria, though the dataset has been found to contain some inconsistencies. Inaccurate data that has been found in these datasets has been removed, but because of the difficulty of reporting casualties in Syria, this should not be considered a 100 percent accurate or exhaustive documentation of Syrian war deaths. Indeed, it almost certainly is affected by a selection bias that favors reporting casualties in more scrutinized areas while neglecting violence in more remote areas. The VDC has also noted that some families decline to report casualties for fear of being targeted again. What the map demonstrates is the escalation of the conflict -- with data from March 2011 through the VDC's Nov. 21, 2013 report -- and its quick descent from being a smattering of violence to a multi-front war with militias challenging the military (and other militias) almost everywhere at once. What it can't show, of course, is the horror and destruction of this war. Jacopo Ottaviani