The diaries of Pedro de Rivera and the Marques de Rubi, written in the eighteenth century during inspections of the far northern frontier of New Spain, are crucial documents for studying and understanding the Spanish presence on the frontier of what would one day be Texas. Rivera's diary, previously unavailable in English translation, and the heretofore-unknown Rubi diary are both presented here, carefully placed in historical context by Jack Jackson and William C. Foster.

Because of Spain's tenuous hold on the distant frontier, Rubi and Rivera saw it as an imaginary possession - the king's domain in name only.

To understand Texas and its adjacent provinces at this formative time, students and scholars of the Borderlands must examine the records left by these two military expeditions. These remarkable documents contain fascinating insights into the early Spanish road systems, the early towns and missions, the Indians, and the flora and fauna. Each diary has an introduction, and detailed route maps and annotations are provided. Following the diaries and related documents, each inspection is assessed in depth.