The Journal of William Maclay is a published version of a diary kept by William Maclay during his tenure as a United States Senator representing Pennsylvania, a position in which he served from 1789 to 1791. Maclay began keeping the diary within two months of taking office and kept it almost daily during the 1st United States Congress. It is one of few accounts of the early United States Senate; sessions would not become open to the public until 1795.