The Orendorff family was among the first settlers in McLean County, when brothers William and Thomas Orendorff traveled to Blooming Grove in 1823 from Sangamon County. The Orendorffs are credited with naming Blooming Grove, establishing farms and families in McLean County, and holding massive family reunions beginning in the 1880s.

The collection contains documents dating from as early as 1848, a deed for school property from William and Malinda Orendorff and until 1984, when an Orendorff family reunion took place in McLean County. The collection contains McLean County histories written by Orendorff family members, correspondence, and family reunion records.