The Brotherton Family Collection contains over 300 letters, newspaper clippings, newspapers, and family papers. The letters were written in the 1850s and 1860s by friends and family of William H. and Sadie Brotherton. The letters represent the Civil War era with letters that discuss the election of Abraham Lincoln and letters written by William Brotherton from a Confederate Prison at Richmond, Virginia. Most letters were written prior to the Civil War. There are also post-war letters written to William from his brother David, who served in the Army during the battles with the Navajo in New Mexico. He was part of the pursuit and capture of Chief Joseph and Sitting Bull.

The collection also contains newspaper clippings and copies of newspapers.

There are also handwritten papers, with many written by William Brotherton. These consist of papers related to a committee that William participated in, some financial documents, flyers, fragments, and other writings. The writings contain poems, songs, and essays.

Series I: Correspondences contains letters written to Sadie and William Brotherton, along with a few letters written to others. Some of these letters do not specify who it written to or from. These additional letters are sorted together in chronological order. All other letters are organized by the recepient, Sadie Brotherton or William H. Brotherton. Sadie's letters primarily consist of letters from William, her immediate family, including one of her sisters and two of her brothers, her extended family members, and her friends. William H. Brotherton's letters were primarily written by his siblings, especially his brother James. He also received letters from extended family members, friends, and Sadie.

Series II: Newspapers primarily contains newspaper clippings of poems. There is also a copy of the New York Tribute from 1887. Another folder contains a newspaper clipping that held a lock of hair inside of it, and the hair is included in the folder.

Series III: Papers consists of family paper documents. There are business cards for William H. Brotherton, committee papers, financial documents, printed flyers, written fragments, a marriage announcement for William and Sadie's daughter Helen Brotherton, and writings. The writings consist of poems, songs, and essays. They are not attributed to a specific author and do not have dates. One poem example is a romantic poem, with one stanza, "I look around, and feel along / And then there falls a tear / For oh! Thou art not here my love / For oh! Thou art not here." One of the handwritten song lyrics papers includes a reference to the 'chorus.'