"This is no job for impulsive, timid or inattentive souls," Roberts wrote in the report, which sheds light each year on an issue the chief justice believes should receive the public's attention.
Roberts' message comes as President-elect Donald Trump prepares to fill a Supreme Court vacancy and reshape the lower courts. There are currently more than a hundred vacancies
at the district and appellate court level nationwide, according to the administrative office of the US courts.
In past years, the chief's reports have emphasized issues such as judicial pay, budget cuts and recusal rules.
Roberts, a keen student of the history of the Supreme Court, almost always manages to weave in historical references. This year's report details George Washington's role in appointing 13 original United States district judges, a list that included a general in the Revolutionary War, a signer of the Declaration of Independence and a poet and musician.
"These individuals are not well known in our era, but they launched the new system of United States District Courts and set the course for the important role those institutions would come to play in the new republic," Roberts wrote.
Turning to present day judges, Roberts said that they are not often the focus of public attention but that they play a "crucial role."
"You might be asking," Roberts wrote, "why any lawyer would want a job that requires long hours, exacting skill and intense devotion -- while promising high stress, solitary confinement and guaranteed criticism."
Roberts continued: "The answer lies in the rewards of public service."
Congress has authorized 673 district court judgeships.
Although Roberts said that "unlike politicians, they work largely outside of the public eye," he did not mention the fact that sometimes district court judges find themselves in the middle of a political storm, as when district court Judge Andrew S. Hanen of the Southern District of Texas temporarily stopped
the Obama administration's executive actions on immigration in 2015.
The programs at issue never did go into effect after a deadlocked Supreme Court blocked them
earlier this year.
On the current court, only Justice Sonia Sotomayor has served as a district court judge. Trump's list of 21 potential Supreme Court nominees is dominated by appellate court judges and state Supreme Court justices but it also includes Judge Amul Thapar of the Eastern District of Kentucky, the home state of Senate Majority Leader Mitch McConnell.