The development of soil classification and mapping by the USDA Soil Survey up to 1935 is considered. This involved the initial development of a scheme by Whitney based on soil productivity as reflected in the geology cum geomorphology. The thrust of this development was opposed by a very different Russian zonalistic approach, which was much more environmental in character. It was first advanced in the USDA by Coffey, but this was firmly rejected by Whitney. It was next proposed by Marbut, who in addition made use of Glinka's work, but made no references to Coffey's previous efforts. This was highly successful, for it not only took over the USDA system completely, but was expanded to form a global system of soil classification. However, the speed with which this occurred was such that numerous flaws and gaps had been created, which needed to be dealt with and this is considered in Part II.