Joseph Trimble Rothrock was born on April 9, 1839, in McVeytown, Pennsylvania, to a German farming family. Agriculture, the environment, and nature were an important part of Rothrock's early education. His love for nature grew when he attended Tuscarora Academy of Academia in Juniata County. The academy's land was so special to Rothrock that he later purchased it as an adult, and the forest was named after him as Rothrock State Forest.

Following Tuscarora Academy, Joseph Rothrock attended Freeland Seminary (now Ursinus College) in Montgomery County, Pennsylvania. He later went on to attend Harvard College where he graduated with a B.S. in Botany in 1862. Following his graduation from college, Rothrock enlisted in the Union Army. He eventually became a captain in the 20th Pennsylvania Calvary but had to end his service on June 6, 1864, after being seriously wounded at the Battle of Fredericksburg. Rothrock then attended the University of Pennsylvania where he received an M.D. in 1867.

Following graduation, Rothrock was a professor of botany, human anatomy, and physiology at the Agricultural College of Pennsylvania (now The Penn State) from 1867-1869. While teaching at the college level, he married Martha E. May, daughter of Rev. Addison May of West Chester, Pennsylvania, on May 27, 1868. The couple moved to Wilkes-Barre in 1869 where Rothrock practiced medicine and helped to found the Wilkes-Barre Hospital. Rothrock helped to found many other institutions in the state of Pennsylvania, including the North Mountain School of Physical Education, a school for boys on Lake Ganoga near Wilkes-Barre.

In 1873, Joseph Trimble Rothrock decided to stop practicing medicine and concentrate on botanical research. From 1873 until 1875, he was both a surgeon and botanist for the United States Engineers, although he spent most of his time studying botany. During this period, Rothrock named many new botanical specimens. Following his time with the United States Engineers, Dr. Rothrock took a position at the University of Pennsylvania as a professor of Botany as well as a faculty member for the Department of Medicine. In 1877, he was named the Michaux Lecturer for the promotion of botany and forestry and held the position until his leave in 1891.

Dr. Rothrock enjoyed traveling and spent some time studying at the University of Strassburg, then in Germany. His most significant trip, however, was during the summer of 1884 when he traveled up and down the Chesapeake and Delaware Bays. Rothrock wrote about his experiences in one of his most famous pieces of writing, a book entitled Vacation Cruising in Chesapeake and Delaware Bays. Written in 1884, the journal style book was published not to detail the research aspects of Rothrock's trip but, instead, to share his personal thoughts on his summer adventure. Rothrock began the trip in June of 1883 on the 34 foot sloop Martha. For three months Rothrock sailed on both the Chesapeake Bay and the Delaware Canal, beginning at Elk River in Maryland, going south to the James River in Virginia, and sailing north again to his starting point. While the book did not claim to be research oriented, Rothrock did write a great deal about topics he was interested in, such as fossil remains, geological formations, and early American settlements. Throughout the piece, Rothrock takes on a number of different tones and focuses on many different subjects that were important to him. These include military, medical, nature and conservation, and historical tones and themes. Although the book was not intended to be a scientific journal, Rothrock does incorporate scientific names for wildlife along with history of and facts about the region. Photographs are also included, giving the reader a sense of where Rothrock was during his summer journey.

Rothrock's writing style is unique in that it provides a great deal of information while still easy to understand by the average reader who does not have a great deal of scientific knowledge and background. Dr. Rothrock's book also provides personal thoughts on the journey, giving the writing a journal quality. He ends his piece by saying,

In spite of its storms and its calms, its over-dreaded mosquitoes, and its alleged malaria, I haved come to think of the Chesapeake Bay as my sanitarium. I know that I come back from my trips there stronger than when I start on them. It is a soul-expanding process simply to gaze out on the water, to study the features of the headlands, and to conjecture I what time and by what agencies they were formed.

The trip was so inspirational that Joseph Rothrock's grandson and his wife took the same trip 100 years later. The book Chesapeake Odysseys recounts the trip of Rothrock's grandson and includes the original text from Rothrock's book.

After returning from his trip, Rothrock focused on forestry in Pennsylvania. On May 26, 1886, Rothrock gave an important lecture on deforestation in Pennsylvania. Following the lecture, the Pennsylvania Forestry Association was created, and Dr. Rothrock was elected its first president on November 30, 1886. As president of the organization, Rothrock traveled throughout the state, giving lectures on deforestation and other forestry topics. Rothrock proved to be a success both as a leader and as an expert in forestry. In 1893, the governor of Pennsylvania commissioned Rothrock to study the state's resources and to report to the state legislature two years later, in 1895. His research once again proved him to be a leader and expert, earning him the title of the first Commissioner of Forestry under the Secretary of Agriculture. He remained commissioner of the department until 1901.

Rothrock also played a large role in the communication between the government and the public on the topics of forestry and the environment. Forest Leaves, a quarterly newsletter, was established to tell the public about Pennsylvania's privately owned forestlands. Dr. Rothrock served as both editor and a writer for the newsletter until his death.

Dr. Joseph Trimble Rothrock died on June 2, 1922 in West Chester, Pennsylvania at the age of 83. His work still influences those interested in the environment and forestry. Rothrock State Forest still stands, and Forest Leaves continues to be published quarterly.