Hill's Plan of Washington is the earliest official map of the City of Washington, pre-dated only by the pirated miniature magazine edition of the Hill and the pirated miniature magazine edition of the Thackara.
On January 24, 1791, President George Washington announced the permanent location of the national capital, a diamond-shaped ten-mile tract at the confluence of the Potomac and Eastern Branch Rivers. The original survey was performed by Andrew Ellicott and Benjamin Bannaker (a freed slave). In March of 1791, Major Pierre Charles L'Enfant was appointed by Washington to prepare the plan for the city with Ellicott as his assistant. L'Enfant turned out to be difficult to work with, and Thomas Jefferson and Washington ultimately suspended L'Enfant in 1792.
Andrew Ellicott took over the project using L'Enfants plan as a base. Philadelphia engravers James Thackera & John Vallance and Samuel Blodget Jr. were hired to produce engraved versions of Ellicott's manuscript plan. Blodget arranged for Samuel Hill of Boston to engrave the map for him. Both Hill and Thackera & Vallance produced a large official map of the new Federal City (along with minature editions, which appeared in magazines). In addition, an edition of the map was printed in red on linen, as a keepsake.
Hill's official version was issued in September 1792, pre-dating the Thackara edition by several months.