President Trump starts off 2020 having presided over a lower average unemployment rate than any president at a comparable point in office in recorded history.
On Friday, the Bureau of Labor Statistics reported that the unemployment rate held steady at a historically low 3.5% in December. Since February 2017, Trump's first full month in office, the monthly unemployment rate has averaged 3.9%. No prior president has averaged less than 4% over the first 35 months of his presidency. The closest was Dwight Eisenhower, when the rate averaged 4.3% between February 1953 and December 1955.
Modern unemployment statistics did not start being kept until 1948, after Harry Truman's first 35 months in office, so this analysis only starts with Eisenhower. Nonetheless, it does point to the unprecedented nature of this consistently low level of unemployment.