1898 Map of Boston, showing surface lines, proposed elevated lines, connecting surface lines and route of subway, by the Boston Elevated Railway Company, from the Digital Commonwealth - commonwealth js956m25c. (<a rel="nofollow" class="external free" href="https://www.digitalcommonwealth.org/search/commonwealth:js956m25c">https://www.digitalcommonwealth.org/search/commonwealth:js956m25c</a>)
Boston Elevated Railway Company
Digital Commonwealth