This interactive map shows where self-driving cars are being tested around the world

Self-driving car development is one of the biggest trends in the automotive world today — but the companies that are working on autonomous vehicle (AV) systems can't just test their technology on any public road.

Local governments first need to give self-driving pilots permission to operate — which is why, for example, Uber decided to test its self-driving taxis in Arizona rather than its hometown of San Francisco following a very public regulatory dispute with the California DMV.

Now, Bloomberg Philanthropies and the Aspen Institute has released the Global Atlas of Autonomous Vehicles (AV) in Cities that shows where all self-driving car development projects are being tested around the world. The guide is specifically focused on urban areas where the local governments are "playing a substantial role" in the work, with the goal of organizing information about the various projects to help cities learn from the other efforts currently underway.

The project is part of the larger Bloomberg Aspen Initiative on Cities and Autonomous Vehicles, which aims to help cities prepare for AVs by bringing mayors together and pooling their expertise and resources to develop a framework for launching pilots and adopting the technology.

The Atlas profiles 35 "Piloting" cities, which are either hosting or have announced plans to host AV test program on public roads. Each point on the map lists more specific details about the city's priorities, partners, and exactly what its pilot program is focused on developing.

A shorter list of 18 locales are tabbed as "Preparing" cities, which haven't committed to any specific pilot programs but have publicly begun to examine the impact AVs might have.

There are projects operating around the world, with representatives from nearly every continent. We're still in the early days of municipal Av development, however — most of the cities only launched their projects within the last three years, and a subset of 30 cities surveyed described multiple obstacles to expanding their programs even further, most of which boil down to a lack of understanding or interest in the burgeoning technologies.

The Atlas will undoubtedly add more entries rapidly as city officials recognize the need for AV legislation and private self-driving technologies mature and companies expand their projects to public test projects. The list of cities already appears to be need an update — GM's Cruise Automation and the New York Governors' Office announced last week that the company planned to work with the DMV and State Police to begin an AV pilot program on the streets of New York City.