Human activities are influencing Earth's systems. Combine our effects with the natural dynamism of climate and ever-changing habitat structures and we have an important opportunity to quantify, evaluate, and predict how biodiversity responds to change. Birds react quickly to modifications in habitat availability and characteristics, so quantifying their distributions and abundances can be especially informative. Here, we provide an overview of our strategies and efforts to create an exactly repeatable benchmark of the distribution and abundance of birds in Oregon early in the twenty-first century. The effort was designed to provide future society with an opportunity to understand more clearly how birds respond to change by leaving a legacy of high-quality, accurately geo-referenced bird-count data. By implementing a simple, yet elegant, sampling design, involving more than a thousand citizen scientists and a few professional ornithologists, we established an unprecedented opportunity for before-after comparisons of population sizes and geographic distributions. Our approach offers future researchers the opportunity to replicate our work using exactly the same methods and look back with 20/20 hindsight to understand responses of birds to change over time and space. Hence, the project is named Oregon 20/20 Birds. Launched in 2011, the decade-long data-collection effort produced counts from more than 20,000 locations by professionals using methods that allow statistical adjustments for detectability and availability of birds, plus more than 50,000 locations where stationary counts were conducted at accurately georeferenced sites by professionals and citizen scientists. Here we summarize information on the project design, approaches for involving citizen scientists (birders using eBird), decision processes for selecting and comparing eBird data with professionally gathered data, and project goals. Results will be reported in future journal articles and books. In addition to providing legacy data for comparison with future repeat surveys, the project also provides a unique resource for addressing current questions in ecological, biogeographical, and evolutionary fields of study, as well issues involving conservation and management of Oregon's birds