Robert William Karrow, Jr. was born in Milwaukee, Wisconsin, 5 August 1945, and educated in the public schools of Hartland, Wisconsin. He received the B.S. degree from the University of Wisconsin--Milwaukee in 1968 and the M.S.L.S. degree from the University of Wisconsin--Madison in 1971. Since July 1971, he has been employed at the Newberry Library, first as Map Cataloger, from 1975 as Curator of Maps, and, from 1989, as Curator of Special Collections. He is the author of Mapmakers of the Sixteenth Century and their Maps (1993) and numerous articles and book reviews. He received the Ph.D. in history from Loyola University of Chicago in 1999 with a dissertation on Intellectual Foundations of the Cartographic Revolution.

One of four "Great Surveys" of the American West in the nineteenth century, the "U. S. Geographical Surveys West of the 100th Meridian" were carried out under the auspices of the Army Corps of Engineers. The Survey grew out of work done by First Lt. George Montague Wheeler (1842-1905) in Nevada in 1869. The following year, Wheeler presented a plan for a uniform topographical survey of that part of the country lying west of the 100th meridian of longitude. The area, some 1,400,000 square miles, would be covered by 95 rectangular sheets each comprising 2° 45' of longitude and 1° 40' of latitude, at a uniform scale of eight miles to one inch (1:506,880). Over the course of eight seasons (1871-1878) the survey managed to map approximately one-quarter of the projected total. Early on it was decided to divide at least some of the sheets into quarters, resulting in maps at a scale of four miles to one inch (1:253,440). In addition, some of the topographic "base maps" were overprinted with colors to show geological formations or land use. With three different series, then, and two different scales, the publication history of Wheeler Survey maps is quite complicated

The Survey relied on annual appropriations from Congress, which began to view with disapproval the fact that four separate federal organizations were involved in western mapping. The others were Ferdinand V. Hayden's "Geological and Geographical Survey of the Territories" (under the Interior Department), John Wesley Powell's "Geographical and Geological Survey of the Rocky Mountain Region" (under the Smithsonian Institution), and Clarence King's "Geological Exploration of the Fortieth Parallel," also under Army auspices. In 1874 the Committee on Public Lands, chaired by Rep. Washington Townsend, held rather contentious hearings on the alleged duplication of effort, and some minor adjustments followed. By 1878, however, the issues came to the fore again and this time Congress invoked the aid of the National Academy of Sciences, who appointed a committee to report on the matter. Following the recommendations of this committee, in the spring of 1879 Congress ended appropriations for the Hayden, Powell, and Wheeler surveys (King had already completed his work the previous year) and established in their place the U. S. Geological Survey. With allocations from the Army, Wheeler devoted another 5 years to publishing maps for which field work had been completed and producing reports, the last of which was published in 1889. Wheeler himself was broken in health and spirit. He resigned his commission in 1889 (he had reached the rank of Major) and went into private practice, dying in New York City in 1905.

Despite its premature demise, the Wheeler Survey could take credit for several important accomplishments. The published maps did provide relatively large-scale and accurate maps for about one-quarter of the target area, with relatively complete coverage for the southwest. The geodetic techniques which the survey had developed by mid-decade were of a high order of accuracy and precision, and they pioneered in the use of the telegraph for longitude determinations. The series of land use maps, though very incomplete, was the first of its kind in this country. Furthermore, the Wheeler Survey employed a number of important topographers and scientists, many of whom went on to distinguished careers; among them James Gardiner, Gilbert Thompson, Louis Nell, G. K. Gilbert, and Timothy O'Sullivan.

Beginning in 1845, the U. S. Coast Survey experimented with using the electrical telegraph as a way of transmitting time signals for use in determining the longitude of places. Over the next two decades, the Coast Survey perfected its methods, which became known as the "American system" for communicating time signals. The Wheeler Survey adopted telegraphic methods for determining longitude at its inception in 1869, and continued to refine its methods.