Primary sources, comprise a number of different types of resources, but primarily they are fall into a couple of distinct categories:
(1) materials created contemporaneously to a timeframe or event in history
(2) materials created by a person or entity which your are researching.
These sources provide insight about a particular topic helping to provide a deeper understanding of a historical period, event, or individual, because they are direct cultural, historical, or ephemeral products the time period, event, movement, or person you are studying. Depending upon what you're studying, what you use as a primary source and how you find them can vary. Very often in historical research you will find yourself accessing print and/or digital archives.
Here are some examples of different types of primary sources you may use in your research:
Given the possibilities for different types of primary sources you might use, think about the different places you might find sources that support and contextualize your work.
This page provides a list of places to begin looking for primary source materials for your project.
"Focuses on critical aspects of anthropogenic change, with unique and rare archival collections from multiple, global sources [...] featuring data-heavy collections on Deforestation, Agriculture, Livestock, and Fisheries (Food Production); Ecology, Botany, Biodiversity, and Extinction; Water Sources, Irrigation, Wetlands, and Hydrology"
Trends and Policy: U.S. Environment merges content from a variety of sources and presents them in a unique interface designed to connect various environmental policies of the United States to their trending results. Included in this collection are all environment-related public laws and hearings, Legislative branch reports, Executive branch reports and data, press releases, and present-day and historical news articles.