The early modern era (usually taken to be 1868-1945 in Japan) was a transition period during which colloquial standard Japanese developed through a process of unification of the spoken and written styles. The basis of this standard Japanese was Tokyo dialect. In this respect, it is known that those who were not from the capital found it difficult to adapt their local dialects to the standard language. One can therefore assume that some dialect interference may be observed in the works of writers of the time who came from provincial areas. The study aims to illustrate such dialect interference in the usage of standard Japanese among people from the Tohoku region. For this purpose I analyze data from my original corpus of the works of Kenji Miyazawa (Iwate Pref.) and Hirosuke Hamada (Yamagata Pref.), both known as writers of children's stories, as well as from other corpora of modern Japanese for comparison. Particular attention is paid to the question of how their usage of the standard particle e is related to that of the dialect particle sa.