After the war, Ellicott returned home to Ellicott's Mills until he was appointed, in 1784, a member of the survey group tasked with extending the survey of the
Mason-Dixon line for the borders between Pennsylvania /
Delaware with
Maryland that had been abandoned in 1767 and then been stalled during the war. In this survey, he worked alongside
David Rittenhouse and Bishop
James Madison, making first connections with the scientific society of Philadelphia. Following the death of their second son, the Ellicotts moved to Baltimore in 1785, where Andrew taught mathematics at the Baltimore Academy and was even elected to the
Maryland General Assembly (state legislature) in 1786. The same year, he was called upon for a survey to define the western border of
Pennsylvania with the
Ohio Country. This "Ellicott Line" (running north–south at longitude meridian 80°31′12″W) later became the
principal meridian for the surveys of the future
Northwest Territory of the United States. His work in Pennsylvania intensified his ties with Rittenhouse and other members of the
American Philosophical Society, to which he had been elected a member in 1785, and led to encounters with
Benjamin Franklin and
Simeon De Witt. When he was subsequently appointed to lead other surveys in Pennsylvania, the family moved again in 1789 to
Philadelphia. By recommendation of Franklin, Ellicott got a position with the newly established government under the
Constitution and was tasked by first President
George Washington to survey the lands between
Lake Erie and Pennsylvania to determine the border between
Western New York and U.S. federal territory, resulting in the
Erie Triangle. This survey, during which he also made the first topographical study of the
Niagara River including the
Niagara Falls, gained Ellicott a reputation for superb accuracy in surveys. (2005) From 1791 to 1792, at the request of
Secretary of State Thomas Jefferson, Ellicott worked under the direction of the three commissioners that President
George Washington had appointed, surveying the boundaries of the federal
Territory of Columbia, which would become the
District of Columbia in 1801, containing the Federal City also then becoming known as
"Washington City". Ellicott began his survey in February 1791, just prior to the arrival of L'Enfant. He was assisted in this survey first by the free
African-American astronomer
Benjamin Banneker and then by Ellicott's brothers,
Joseph Ellicott and
Benjamin Ellicott. Ellicott's team put into place forty boundary stones approximately 1 mile (2 km) apart from each other that marked the borders of the Territory of Columbia of (see:
Boundary Markers of the Original District of Columbia). Most of these stones remain in their original positions. As
engravings on many of the stones still show, Ellicott's team placed those that marked the southwestern /southeastern border with Virginia in 1791, and those that marked the northwestern / northeastern border with Maryland in 1792. On January 1, 1793, Ellicott submitted to the three commissioners "a report of his first map of the four lines of experiment, showing a half mile on each side, including the district of territory, with a survey of the different waters within the territory". The
Library of Congress has attributed to 1793 Ellicott's earliest map of the Territory of Columbia that the Library holds within its collections. , 1887). During 1791–1792, Ellicott also surveyed the future city of Washington, which was located within a relatively small area at the center of the Territory of Columbia along the northern bank of the
Potomac River at the confluence with its Eastern Branch (known today as the
Anacostia River). Ellicott also served under the Commissioners' supervision in this effort. He first worked with
Pierre (Peter) Charles L'Enfant, who had prepared the initial plans for the future capital city during the early months of 1791 and had presented one of these early plans to President Washington in August of that year (see
L'Enfant Plan). During a contentious period in February 1792, Ellicott informed the Commissioners that L'Enfant had not been able to have the city plan engraved and printed as a map on paper and had refused to provide him with an original plan that L'Enfant was then holding. Ellicott, with the aid of his brother,
Benjamin Ellicott, then revised the plan, despite L'Enfant's protests. Ellicott stated in his letters that, although he was refused the original plan, he was familiar with L'Enfant's system and had many notes of the surveys that he had made himself. It is therefore possible that Ellicott recreated the plan. Ellicott's revisions realigned and straightened the diagonal
Massachusetts Avenue, eliminated five short other radial avenues and added two others, removed several plazas and straightened the borders of the future
Judiciary Square. As the conflicts grew between the contending parties shortly thereafter, President Washington dismissed L'Enfant. Ellicott gave the first version of his own plan to James Thakara and John Valance of Philadelphia, who engraved, printed and published it. This version, printed in March 1792, was the first Washington city plan that received wide circulation. relieved to escape the political pressures surrounding that venture. In 1794, Ellicott accepted a commission from the Commonwealth of Pennsylvania to plan the city of
Erie on the southeastern shore of
Lake Erie, giving the Keystone State a future port on the
Great Lakes and its increasing trade. He spent the next two years with this task, plotting a road from
Reading, Pennsylvania, to
Presqu'Isle, where the port city was to be built, and also supervising the construction of
Fort Erie. In 1796, George Washington commissioned Ellicott as the U.S. representative on the commission for the survey of the southern border between the
Spanish territories along the
Gulf of Mexico coast in
Florida and the United States as negotiated in the
Treaty of San Lorenzo (also known as
Treaty of Madrid) of 1795. Ellicott travelled with a military escort from
Pittsburgh via the
Ohio and
Mississippi rivers and worked together with Spanish commissioners, despite many difficulties, for the next four years. Ellicott's assistants on the survey were his son Andrew Ellicott Jr. and
David Gillespie. A Mississippian, possibly a descendant of
Isaac Guion, hinted at some of the difficulties Ellicott had in the unfamiliar political and social climate of pre-territorial Mississippi, writing, "Ellicott was a Pennsylvania quaker by birth and education; by some knowledge of natural history, astronomy and botany, he had recommended himself to Mr. Jefferson; but he was vain, weak, ambitious and obstinate, and wholly unfit for a position that demanded something more than civil engineering. Pope was a mere martinet, and easily became the tool of Ellicott." Another "Ellicott's Line" from this survey, running along
latitude parallel 31° North, still defines the border today between the future states of
Alabama and Florida. One of his many stone markers for the boundary line, the
Ellicott Stone, is now located within a historical park about a mile south of
Bucks, Alabama. In 1798, Ellicott complained to the government about four American generals receiving pensions from Spain, including General in Chief
James Wilkinson, raising the specter of treason, which later involved Vice President (during Jefferson's first term),
Aaron Burr. Ellicott showed considerable diplomatic talent during this joint project to bring it to a successful completion, and he presented his final report with maps to the government in 1800. (The
Mapping episode of
Philip Morrison's miniseries
The Ring Of Truth illustrates Ellicott's surveying methods from
Ellicott Hill in
Natchez,
Mississippi, which is now another
National Historic Landmark.) The following
Adams administration, however, then refused to pay Ellicott for his work done in this survey, and even refused him access to his maps he had submitted with the report. He was forced to sell some of his possessions, including books from his library, in order to support his family. Finally the maps were released in 1803 under the subsequent Jefferson administration, and Ellicott published his
Journal of Andrew Ellicott detailing the Florida survey, including the maps. Jefferson, now president, then offered Ellicott the post of
Surveyor General of the Northwest Territory. However, Ellicott refused the appointment. His prior negative experiences with the government political administrations may have had something to do with this, but at the age of 49, he also wanted to spend more time with his family and feared that this new position might require him to travel too much. Ellicott instead accepted an offer by Pennsylvania governor
Thomas McKean and took a position as Secretary of the Pennsylvania Land Office. The family moved to
Lancaster, Pennsylvania, and Ellicott seemed content with a clerk's job that left him enough time for his own scientific and private interests and that provided a steady income for the family. The
Andrew Ellicott House, in Lancaster where he resided from 1801 to 1813, was listed on the
National Register of Historic Places in 1972, by the
National Park Service. Also in 1803, President Jefferson engaged Ellicott as a mentor and teacher for
Meriwether Lewis, one of the leaders of the
Lewis and Clark Expedition that was to start the following year. From April to May 1803, Lewis stayed at Ellicott's home and studied survey techniques, and Ellicott made many recommendations on the expedition's equipment and survey procedures that were later followed. The two men apparently got along well. When
Simon Snyder followed McKean as governor of Pennsylvania, he fired Ellicott in 1809 due to political differences. A prominent supporter of Snyder was former General in Chief
James Wilkinson, one of the four generals that Ellicott had denounced eleven years earlier and had come under a cloud of treason, along with Vice President
Aaron Burr. Ellicott returned to private practice and was hired in February 1811 by
David B. Mitchell, then governor of
Georgia, to re-survey the border between Georgia and
North Carolina to settle a
border dispute between these two states. Although he started out in July, his expedition was delayed and had to work throughout the hard winter. Ellicott confirmed earlier findings that the border, which was supposed to follow
latitude 35°N, was several miles further south than the Georgians claimed. His report was not well received by the Georgian administration, who furthermore refused to pay his fees. Ellicott returned in July 1812 to Pennsylvania. In 1813, Ellicott accepted a position as a professor for mathematics at the
United States Military Academy at West Point, and the family left Lancaster and moved to
West Point, New York. In 1817, Ellicott was again called upon to participate as astronomer in a field survey, namely a re-survey – agreed upon in the
Treaty of Ghent – of the
Collins–Valentine line. It was the last significant survey that he performed. Ellicott died three years later from a
stroke in his home at West Point. ==In memoriam==