Preparation of the material presented here began in 1967. Harry Crosby was retained by Copley Books of San Diego to illustrate The Call to California, a work dealing with the Portola-Serra expedition of 1769. In order to obtain photographs of the expedition’s route, he followed its trail from Loreto to San Francisco. South of Mission San Vicente (see Map 11) this route could not be pursued by automobile. This stretch of some six hundred miles was traced by the use of riding and pack mules. The part of that route between Loreto (see Map 1) and Rancho San Agustin (see Map 8) was more than simply a route employed by Portola and Serra, it was the camino real of the mission period. Crosby was the first to seek out and follow that old route since it fell from regular use nearly a century before. A thorough account of that trip was published as The King’s Highway in Baja California (Copley Books, 1974).
Crosby’s companion on the 1967 trip was Dr. Paul B. Ganster (now professor of history at Utah State University). Ganster kept a detailed set of trail notes which included all the placenames available from local people, and a set of sketch maps which showed the complexities of trail and terrain. On subsequent muleback trips Crosby was able to trace, locate, and chart several alternate routes which were built and used during the mission period. He also went back over much of his 1967 route, particularly the stretch from La Purisima to Santa Gertrudis.
The series of twelve new maps presented here was prepared by Daira Paulson who worked closely with the author to create this graphic presentation of his data. (Ms. Paulson is a graduate student in geography with emphasis in cartography at San Diego State University.) The base map from which this was developed was that published by: “Comision Intersecretarial Coordinadora del Levantamiento de la Carta Geografica de la Republica Mexicana, Primera Edicion: Terminada y Publicada en 1958” (scale 1:500,000).
This base was enlarged to its present scale of approximately 1:280,000 by photographic means and the outlines traced along with the desired watercourse representations and a selection of elevation contours. The elevations shown on the finished map were chosen to give the reader a sense of surroundings, that is to suggest to him, at any particular place on El Camino Real that he is on a mesa, in a valley or crossing a pass. In order to achieve this effect the three most relevant contours were chosen independently for each of the twelve maps. In those maps on which the trail runs through generally lower areas, the contours selected were 200m, 600m and either 1000m or 1200m. Those maps which show the trail on higher ground have contours at 400m, 800m and either 1200m or 1400m. In addition, for maximum effect and in order to make the maps part of a continuous mosaic, there are occasional jumps from one contour to the next higher or lower (without indication that this has occurred). As a result the contours do not provide absolute altitudes but are designed to be useful in estimating the character of terrain as it rises from the trail rather than sea level. (absolute elevations can be obtained from the base map or from the newer series of 1:50,000 maps now being prepared for CETENAL (Comision de Estudios del Territorio Nacional) and published in Mexico.
In some critical locations the watercourse data has been refined by using aerial photographs. In addition, these photographs have been laboriously analyzed from visible muestras or showings of El Camino Real. Wherever they could be found they were used in placing the trail on the final map. Paul Ganster’s field notes and sketch maps have also been extensively compared and have been invaluable in relating the trail followed to mapped topography.