There are many informal physics education programs across the country. However, the available information about these programs varies widely and can be difficult to find. Without this knowledge, it is difficult for individual informal physics efforts to be understood as part of a broader national landscape of physics learning outside of the classroom. In this paper, we describe the development of study design and implementation to map the complex landscape of informal physics in the United States. We seek to determine the best ways to collect meaningful and comprehensive data from the wide-ranging and diverse formats of informal physics programs facilitated by academic institutions. Data was obtained from initial web searches for programs, surveys and interviews of program facilitators, and site visits of program events and activities. This data was analyzed along with participants' feedback to produce iterations of the survey and interview protocol. We report on challenges and outcomes from our attempts to collect information about programs in Michigan as a test case for the national landscape. These methods can also be used in other informal education studies to gather program information.