The collection includes 316 personal letters, 313 of which were written by Lawrence Shields to Clara Kinney, June 1898 to May 1902. Most of the letters were written from Mexico, with the notable exception of those from 1898 (before Shields's departure) and June-November 1900 (when Shields was in Seattle, Washington). Through 1899 and 1900 Shields typically wrote Kinney 6 to 10 times per month, without expressing the profundity of his feelings for her. In March 1901 he wrote Kinney of his love, and was rebuffed; his response, severing the relationship (16 March 1901), includes a resume of his feelings over the previous several years. In August Kinney resumed writing, to Shields's delight; a subsequent visit to Ohio (December 1901/January 1902) appears to have resulted in plans to wed. On his return to Mexico Shields wrote on an almost daily basis, until the letters break off at the end of May 1902.

While the letters of 1902 are first and foremost love letters, those of earlier years (1899 and 1900, especially) provide an extended account of Shields's experience of Mexico, as a newly arrived member of the American expatriate community. By the turn of the 20th century most of Mexico's industry, and a great deal of its land, were in the control of foreign interests, American, British, French, and German. In the main, Shields worked and socialized within this "colony," and his opinions reflect its biases. His profession did allow for interaction with prosperous Mexicans, whom he visited in and outside Mexico City, on their rural estates. He had some occasion to travel, to Cuernavaca (February-March 1899); Tehuacán (November-December 1899), and Silao (January 1900), among other places. His letters incorporate descriptions of the places he lived and traveled, his recreations (the bullfight, the theater, parties and festivals), members of the business and diplomatic communities, Mexican life and customs, the social classes, and politics. On the occasion of President Porfirio Díaz's fifth inauguration (December 1900), he writes: "He has ruled this turbulent country for twenty years with a more despotic power than that of the czar: he is the government. But all give him credit of being a statesman: under his rule rebellions and revolutions are a thing of the past. Now the government is upon a sound and stable basis. Never in its history has Mexico made such progress." (letter of 7 December 1900).