United Sates census records are available for 10-year intervals from 1790 to 1940, although the 1890 records were largely lost in a fire. The following table shows the numbers of Kelsall entries counted from each census (relying on the Ancestry search engine). Also shown are the numbers for other similar names that are considered to misspellings or alternative spellings of the Kelsall name.
The table separates variants that are considered to be misspellings or alternative spellings of the Kelsall name, from other names that more likely have a different origin. This distinction is clear in some cases (e.g. Kelsey, Kelso) but subjective in other cases (e.g. Kelsel which is excluded based on examination of the individual census records which suggest different origin). This analysis is like that presented for the UK census but more variant names are excluded from the US records because of the wider range of sources from various European countries.
The following graph shows the numbers from the census for both Kelsall and Kelsall + variants. Also shown are extrapolations to the current population based on the 1880 Kelsall (and Kelsall + variant) population and the increase in the total US population. The trend suggests that Kelsall increased slightly more rapidly than the general US population especially in the 1880 to 1900, and 1920 to 1930 periods possibly highlighting times of increased immigration.
The following table shows census returns for Kelsall plus variants organized by state.
The first Kelsall or variant recorded in the US Federal Census is in 1790, Agness Kelsall of Beaufort, South Carolina. Agness owned 30 slaves and lived in a total household of 30 people. Agness is the last record in the census of the Moutrie/Bellenger tree. She died in 1817.
I have found no Kelsall or variants in records on Ancestry for the 1800 to 1820 United States Census.
Other historical records from the period before 1830 are described here. Excluding a few generally isolated records, the story of Kelsall immigration to the United Sates is told in the census records at these links:
1890 United States Census: the 1890 records were largely lost in a fire
1910 United States Census
1930 United States Census