See also: Supreme Court Caseloads, 1880-2015 (graphs)

Prior to 1878, no official statistics on the workload of the Supreme Court were reported. An important exception is statistics on the Supreme Court docket for the years 1823 to 1846 submitted during congressional debate on the circuit duties of the Supreme Court justices in 1848. The best source of information on the Court's workload during this period is the Court's docket books, available on microfilm at the National Archives. The cases filed with the Court were consecutively numbered, based on the date they were filed, in two series- one for cases brought under the Court's original jurisdiction and the other for cases based on appellate jurisdiction (with the exception of some original jurisdiction cases filed between 1792 and 1801 that were not numbered). Between 1803 and 1905, the Court produced two kinds of docket books: a rough docket and an engrossed docket. The rough dockets included information on all unfinished and new cases that were before the Court each term. The engrossed dockets present information on each case in order of docket number and give the complete history of each appellate case based on information in the rough dockets (the original jurisdiction cases are only included in the rough dockets between 1829-1905). Each engrossed docket entry includes the date the case was filed, any action taken on the case at each term, including continuations, date of argument, and the date and details of disposition. After 1905, the Court maintained a single series of dockets.

The first government reports on the caseload of the Supreme Court were included in the Annual Report of the Attorney General of the United States beginning in 1878. The statistics for 1878 and 1879 included information on the total cases on the docket, as well as more detailed data on the cases before the Court that involved the United States as a party. In 1880, the Attorney General began reporting more complete information on the Court's original and appellate caseload, including the number of cases filed, the total cases on the docket, the number of cases disposed, and the number of cases carried over to the following term. The Attorney General's report also included data on the number of cases actually argued (including cases argued orally and those argued through printed submissions) and information on the outcome of the appellate cases before the Court (the number of disposed cases reversed, affirmed, dismissed, and settled.) After 1891, the report included information on the number of petitions for certiorari denied, but did not include the total number of petitions received. Beginning with the annual report of 1919 (which presented information on the October 1918 Term), the Supreme Court's caseload statistics were presented in the annual report of the Solicitor General of the United States, which was submitted to Congress as part of the Attorney General's annual report.

The reports of the Attorney General and Solicitor General do not disclose the source of their data on the Court's caseload. The Solicitor General did note in his 1931 report, however, that the data on the Court's October 1930 Term included "each case separately numbered upon the docket of the court," which was "contrary to the practice followed in prior reports of the Solicitor General and brings this report into conformity with the statistics available in the clerk's office." It is unclear how the Solicitor General's method of compiling the caseload data differed in previous years.

Beginning in 1928, Supreme Court caseload information was also published in the Harvard Law Review . In an annual feature titled "Business of the Supreme Court," Felix Frankfurter and other legal scholars presented data on total cases on the docket, the manner of disposition, origins and form of cases reaching the Court, and data on the number of petitions for certiorari granted and denied. Each year's report included information from the previous five years. The Harvard Law Review also presented statistics on the distribution of opinions among the justices and the substance of the law in cases that received opinions. Frankfurter compiled his data through an analysis of the cases published in the U.S. Reports . The Harvard Law Review continued to publish this data through the 1938 Term.

Starting with the 1922 Term, the reporter of the decisions of the Supreme Court included in the U.S. Reports a short summary of the Court's caseload. The short table presented information on the original and appellate dockets separately, indicating the number of cases pending at the beginning of the term, new cases docketed during the term, cases disposed, and cases remaining for the following term. The Supreme Court also began in 1932 to publish caseload statistics in the Journal of the Supreme Court , the publication that contains the official minutes of the Court. The numbers in the Journal are prepared by the Supreme Court's Office of the Clerk. In addition to total cases on the docket, disposed cases, and cases remaining during each term, the Journal presented the number of cases disposed by written opinions, by per curiam opinions, by denial or dismissal of petitions for certiorari, and the number of signed and per curiam opinions. Beginning with the 1970 Term, the Journal also presented data on the number of cases filed during each term.

In the data reported in the Journal , the category "cases" included those cases numbered on the original and appellate docket of the Supreme Court, including petitions for a writ of certiorari and questions of law certified to the Court by the circuit courts of appeals and the Court of Claims. Prior to 1945, petitions for writs of habeas corpus, mandamus, and other extraordinary relief that were accompanied by a motion for leave to file in forma pauperis -that is, filed by indigent litigants who could not afford to pay filing fees-were only placed on the Court's numbered docket if the motion was granted. Beginning in the 1945 term, the Court adopted the practice of numbering all motions for leave to file that accompanied these petitions and placed them on a newly-created miscellaneous docket. Beginning with the 1947 term, these petitions were included in the Court's calculation of total cases on the docket. Note that statistics on the Court's caseload presented by the Administrative Office of the U.S. Courts include the petitions on the miscellaneous dockets for the 1945 and 1946 terms. When a motion for leave to file on the miscellaneous docket was accepted for plenary review, it was transferred to the Court's appellate docket. (No transfer is made, however, if the motion for leave to file is granted and the case is disposed of on the merits by the same order.) The statistics reported in the Journal of the Supreme Court count these cases when docketed and transferred from the miscellaneous docket and again when added to the appellate docket, in effect counting them twice. In 1970, the Court abolished the miscellaneous docket and instead divided appellate cases into original, paid, and pauper cases and ended the practice of transferring cases between dockets.

In 1940, the Administrative Office of the U.S. Courts began to publish statistics on Supreme Court caseloads in its Annual Report of the Director . The Statistics Division at the Administrative Office receives data from the Clerk of the Court but independently produces its own tables. Between 1940 and 1969, the tables in the Director's report presented details on original jurisdiction cases, appellate cases (which combined appeals and petitions for writ of certiorari), petitions for certiorari filed in forma pauperis , and other motions for leave to file on the miscellaneous docket. The Director's report also included a separate table that presented data on the method of disposition. The statistics in the Director's report do not always agree with those published by the Supreme Court in the Journal , however. In the years prior to 1970, the report of the Administrative Office only counted those cases transferred from the miscellaneous to the appellate docket once. Perhaps because of uncertainty over the changes to the Supreme Court's docketing system, the Administrative Office failed to report any information on the Supreme Court's docket for the years 1970-1975. Since 1976, the Journal of the Supreme Court has not counted as disposed those cases granted a plenary review but carried over to the next term for argument. The Administrative Office's annual report counts these granted petitions as disposed, meaning that it shows a larger number of cases disposed each term. Finally, in a number of years, the Journal of the Supreme Court presents a revised total for the number of cases remaining from the previous term; the Administrative Office does not revise that number from year to year.