August 5, 1859. Camp No. 16 at the Rio Florida, 220 miles northwest of Santa Fé, New Mexico:

We have just heard rumors of a fight between our soldiers & the Mormons in the Salt Lake City—these rumors are brought in by Indian traders who came into our camp yesterday on their return from the great rivers we expect to visit—the reports are so extravagant we can scarcely believe them—they speak of battering down houses & killing women & children—so unusual a course for us that I cannot credit the reports—yet the description of the...

On July 13 the Macomb command commenced its adventure into unmapped territory to reach the junction of the Colorado and Green rivers. Briefly, their journey beyond Santa Fé took them up the headwaters of the Rio Grande and across the Continental Divide into the upper drainage of the San Juan, a major tributary of the Colorado River. After they crossed the 37th parallel into today’s Colorado, they entered the eastern limits of Utah Territory, formed in 1850, with this area ceded to Colorado in 1861. They followed a west and northwest course across the headstreams of the San Juan and...

At journey’s end, much work remained for the men of the Macomb expedition as they prepared for their homeward travel. The Army required Macomb to settle his accounts before he returned to Washington. In addition to selling off surplus provisions and equipment to balance the books, he needed to assemble a wagon train and arrange for a military escort to accompany him to Fort Leavenworth. He anticipated that all of his civil employees would accompany him on his homebound path, but two sought to convince the captain that they needed to travel a faster and, seemingly, less dangerous route home....

Additional challenges awaited Macomb and Newberry following their safe return to their homes in the East. Macomb needed to oversee the completion of a final report of the expedition. A high-quality, large-scale map, based on information from Dimmock’s exemplary fieldwork, that fully depicted the region explored by Macomb had to be created. But who would take on the task? Artifacts and other materials gathered by Macomb’s men needed to be submitted to the Smithsonian Institution. In addition, experts in various scientific endeavors needed to study the specimens collected by Newberry and issue their own reports. With a looming Civil War,...

The Civil War broke out on April 12, 1861 and disrupted the plans for a timely report on the findings of the Macomb expedition. Futhermore, it changed the lives of the expedition’s main participants. Ultimately, what happened to the men? What did they achieve? More importantly, what were the major contributions of their San Juan Exploring Expedition?

During the Civil War, Macomb and Dimmock broadened the skills they had developed in the expedition. Macomb served as aide-de-camp to Gen. George McClellan. As the war progressed, the Union Army placed him with a balloon reconnaissance unit and he produced detailed maps...

Before his adventure began, Dimmock procured a pocket diary, published by Denton & Wood of Cambridgeport, Massachusetts. The book’s limited space for daily entries seemed well suited to his tiny handwriting. He also carried along a fine lead pencil and a pen to make notations and a sketchbook for making drawings. (In addition he created a portfolio of other drawings made on the journey. Over time, the acidic content of the paper nearly destroyed his work.) Dimmock wrote his experiences in this printed pocket diary, which included an almanac, printed postage rates, “a blank space for every day in the...

Terby Barnes found this important manuscript in the Rodgers Family Papers on a research trip in 1984 to Washington, D.C. She subsequently transcribed the document and shared it with me. (A typescript of her transcription can be found in the holdings of the Utah State Historical Society, Salt Lake City.) In 2007 I visited the Manuscript Division of the Library of Congress and made my own copy and transcription of the file, published here.

Dimmock wrote the 23–page manuscript on legal-sized paper, possibly supplied from the law firm in Maryland where he worked. In April 1860, Macomb “ran over...

Dr. John S. Newberry apparently made the following condensed record from the expedition diary he kept in the field. The original unabridged version is now lost to history, and only a microfilm copy of his condensed work can be found.

Newberry inadvertently inserted into the abridged diary a number of quotation marks, which indicate that he was quoting himself. He penned much of his diary in telegraphic style and often wrote in incomplete sentences. But he included more elaborately crafted excerpts from his original diary in Macomb’s published report.

The entries from Newberry’s abridged diary, when added to the experiences...

Macomb used his correspondence in part to create his summary report of the expedition. Fortunately, his wife Nannie saved the letters. It appears that she subsequently donated the collection to the Library of Congress.

I have removed most of Macomb’s personal comments, unrelated to the expedition, from the following letters.

Santa Fé, N. M. 4th June 1859.

My dear Wife,

….I am just beginning now my preparations for the summer’s work—that is as well as I can in the absence of pretty much everybody on whom I depend for Carrying out my orders. The Commander of the Department has...

The following letters provide fresh insights into the Macomb Expedition and Newberry’s activities related to the survey. Newberry shared a close friendship with his mentor, Spencer F. Baird, and named his third son after him.

Newberry’s handwriting is very difficult to transcribe. Hastily written, his letters reveal the energy that he devoted to his work.

On the Prairies

May 17th, 1859

My Dear Baird

We left Independence yesterday all right, and are now fairly en route—It has rained almost constantly since we left Washington, and the roads are awful!

We have a coach all to ourselves and are progressing...

The following correspondence illustrates the careful development of Egloffstein’s monumental map of the Macomb Expedition. It represents a compilation of several survey maps and other pertinent primary sources. Nevertheless, it is based primarily on the 1860 manuscript map of the expedition, drawn by Capt. John N. Macomb and Charles H. Dimmock.

The map’s evolution occurred over a two year period during the Civil War. Construction of the map began at the outset of the war. And though the cartographer held emigrant status, he joined the Union effort, served as an officer, and was severely wounded in battle. These events delayed...