Since April 2015 is the sesquicentennial of the end of the Civil War, now is a particularly appropriate time to review the progress of the Corpus of American Civil War Letters (CACWL) project and to suggest directions it might go in the future. Since 2007, we have located and collected images of nearly 11,000 letters and transcribed over 9,000 of these, totaling well over four million words. Of the transcribed letters, just over 6,000 were written by southerners (490 individual letter writers), a corpus extensive enough to begin identifying and describing what features were distinctively Southern in 19th-century American English. We have already mapped many of these features that are especially common in southern letters, for example, fixing to, howdy, past tense/past participle hope ‘helped’, qualifier tolerable, intensifier mighty, pronoun hit, and the noun heap. By way of comparison, we also have a somewhat smaller but rapidly growing collection of 3,000 transcribed letters written by individuals from northern states, and variant features from these letters are also being mapped. The work at present is very preliminary; there are thousands of additional letters to be collected and transcribed, particularly from northern states and from states west of the Mississippi. However, by mapping variants from letters that have already been transcribed, we can begin to get a better understanding of regional differences, as well as how regional features spread westward in the decades before the Civil War. We can also begin to obtain some sense of how American English in general, and particularly its regional dialects, may have changed since the mid 19th century. This article presents a preview of a number of those findings.