Texas was already slipping from the grasp of Mexico when Manuel Mier y Terán made his tour of inspection in 1828. American settlers were pouring across the vaguely defined border between Mexico’s northernmost province and the United States, along with a host of Indian nations driven off their lands by American expansionism. Terán’s mission was to assess the political situation in Texas while establishing its boundary with the United States. Highly qualified for these tasks as a soldier, scientist, and intellectual, he wrote perhaps the most perceptive account of Texas’s people, politics, natural resources, and future prospects during the critical decade of the 1820s. This book contains the full text of Terán’s diary—which has never before been published—edited and annotated by Jack Jackson and translated into English by John Wheat. The introduction and epilogue place the diary in historical context, revealing the significant role that Terán played in setting Mexican policy for Texas between 1828 and 1832.