When doing historical research, it is important to distinguish between primary and secondary sources:
"Primary sources provide first-hand testimony or direct evidence concerning a topic under investigation. They are created by witnesses or recorders who experienced the events or conditions being documented. Often these sources are created at the time when the events or conditions are occurring, but primary sources can also include autobiographies, memoirs, and oral histories recorded later. Primary sources are characterized by their content, regardless of whether they are available in original format, in microfilm/microfiche, in digital format, or in published format." (What Are Primary Sources? Yale University)
Secondary sources are written by someone who was not present during the event or condition under discussion. Authors of secondary sources use primary sources or other secondary sources to gather their information.
These are some common types of primary sources. Some of these source types could be primary or secondary, so each item must be considered individually. For example, a voice mail message could be from someone who experienced an event or it could be from someone telling you what another person experienced.
The UW-Whitewater has one database that provides letters and diaries, but just through 1960. It is listed below.
A better research tool to use would be Research@UWW, which can help locate letters, diaries, and more. The Primary Sources tab has some suggested terminology to aid in finding primary sources. Here are some suggested types of searches:
Primary sources providing a personal view of what it meant to immigrate to America and Canada between the late 1700s and 1960.