The United States Coast and Geodetic Survey (abbreviated USC&GS; known as the Survey of the Coast from 1807 to 1836, and as the United States Coast Survey from 1836 until 1878) was the first scientific agency of the United States government. It existed from 1807 to 1970, and throughout its history was responsible for mapping and charting the coast of the United States, and later the coasts of U.S. territories. In 1871, it gained the additional responsibility of surveying the interior of the United States and geodesy became a more important part of its work, leading to it being renamed the U.S. Coast and Geodetic Survey in 1878.

Long the U.S. government's only scientific agency, the Survey accumulated other scientific and technical responsibilities as well, including astronomy, cartography, metrology, meteorology, geology, geophysics, hydrography, navigation, oceanography, exploration, pilotage, tides, and topography. It also was responsible for the standardization of weights and measures throughout the United States from 1836 to 1901. In 1959, it was assigned the responsibility for U.S. government oceanographic studies worldwide.

By the mid-19th century, the Coast and Geodetic Survey operated a fleet of survey ships that constituted a distinct seagoing service of the United States until 1970. The Survey supported U.S. military operations in wartime, and in 1917 the Coast and Geodetic Survey Corps was created as a new uniformed service of the United States to carry out both wartime and peacetime surveying and related operations.

In 1970, the Coast and Geodetic Survey was abolished when it merged with other government agencies to create the National Oceanic and Atmospheric Administration (NOAA), but its elements were reorganized and incorporated into NOAA as the National Ocean Survey, later renamed the National Ocean Service. In addition to the National Ocean Service, NOAA's National Geodetic Survey, Office of Coast Survey, and NOAA fleet all trace their ancestry in whole or in part to the Coast and Geodetic Survey, and the NOAA Commissioned Officer Corps is the descendant of the Coast and Geodetic Survey Corps. In addition, the modern National Institute of Standards and Technology, although long separated from the Coast and Geodetic Survey, traces its ancestry to the Coast and Geodetic Survey's Office of Weights and Measures.

The United States Coast and Geodetic Survey began its existence as the United States Survey of the Coast, created within the United States Department of the Treasury by an Act of Congress on February 10, 1807, to conduct a "Survey of the Coast." The Survey of the Coast, the United States government's first scientific agency, represented the interest of the administration of President Thomas Jefferson in science and the stimulation of international trade by using scientific surveying methods to chart the waters of the United States and make them safe for navigation. A Swiss immigrant with expertise in both surveying and the standardization of weights and measures, Ferdinand R. Hassler, was selected to lead the Survey.

Hassler submitted a plan for the survey work involving the use of triangulation to ensure scientific accuracy of surveys, but international relations prevented the new Survey of the Coast from beginning its work; the Embargo Act of 1807 brought American overseas trade virtually to a halt only a month after Hassler's appointment and remained in effect until Jefferson left office in March 1809. It was not until 1811 that Jefferson's successor, President James Madison, sent Hassler to Europe to purchase the instruments necessary to conduct the planned survey, as well as standardized weights and measures. Hassler departed on August 29, 1811, but eight months later, while he was in England, the War of 1812 broke out, forcing him to remain in Europe until its conclusion in 1815. Hassler did not return to the United States until August 16, 1815. The Survey finally began surveying operations in 1816, when Hassler started work in the vicinity of New York City. The first baseline was measured and verified in 1817.

With surveying work barely underway, Hassler was taken by surprise when the United States Congress – frustrated by the slow and limited progress the Survey had made in its first decade, unwilling to endure the time and expense involved in scientifically precise surveying, unconvinced of the propriety of expending U.S. government funds on scientific endeavors, and uncomfortable with Hassler leading the effort because of his foreign birth – enacted legislation on April 14, 1818, which repealed most of the 1807 statute. Congress believed that United States Army and United States Navy officers could achieve surveying results adequate for safe navigation during their routine navigation and charting activities and could do so more quickly and cheaply than Hassler, so its 1818 law removed the Survey of the Coast from the Department of the Treasury, prohibited the U.S. government from employing civilians to conduct coastal surveys, and gave the U.S. Army and U.S. Navy responsibility for such surveys under the auspices of the United States Department of War and United States Department of the Navy, respectively. Although the 1818 law did not abolish the Survey of the Coast, it had the effect of removing Hassler from the superintendency and suspending the Survey's operations.

During the 14 years from 1818 to 1832, the Survey existed without a superintendent or civilian workforce and without conducting any surveys. During these years, the Army conducted no surveys, those the Navy carried out achieved unsatisfactory results, and the United States Secretary of the Navy and others repeatedly called on Congress to revive the 1807 law.