Last summer, Sunlight released a series of Open Data Guidelines in reaction to a surge of municipal open data policy making. In anticipation of revamping these policies this summer (to add fresh context, ideas, and exemplary language) and in reaction to a recent surge in open data policy collaboration as evidenced by the interactive Project Open Data and the newly public (beta) Open Data Stack Exchange (or maybe more accurately in reaction to the Meta Open Data Stack Exchange...), we wanted to provide a roadmap to the world open data resources and recommendations that are available to put these resources in context of their evolution over time–a guideline to Open Data Guidelines, if you will. The first step in navigating the open data guidelines out there is to examine the chronology of how they surfaced.

The timeline below provides a landscape of current open data policy guidelines, guidance, and principles that exist and showcases the chronology in which they have manifested, each guideline often directly building off of (or crafted in reaction to) its predecessor. Looking at these guidelines in context exposes the pragmatic and technical evolutions in thought that have occurred under the banner of open data pursuit: from the foundational drive to define what information is legally available (through FOIA and other public records laws) to the trailblazing concept of proactive disclosure (where "public" access means "online" access) to establishing the qualities that make data more accessible and usable (emphasizing structured, bulk data, unique IDs, and APIs). The dialogue for discussing open data policy guidelines has itself evolved from the gathering of smaller open government groups of: Open House Project, Open Government Working Group, the Open Government Initiative, and early collaborative efforts such as the Open Gov Handbook, to the editable Project Open Data and the Q&A Open Data Stack Exchange.