New Jersey census records for the first four federal census--1790, 1800 (except for Cumberland County), 1810, and 1820--have not survived. Except for parts of Hudson County, the 1890 (11th census) records were destroyed in a fire at the National Archives in 1921.
By law, census data on individuals may not be released for 72 years. The 1950 Census population schedules were released in April of 2022.
New Jersey federal census records from 1830 to 1940 can be searched for free at FamilySearch.org. (Registration required.) The 1940 and 1950 censuses are available for searching from the U.S. National Archives.