Present Day Population
I estimate that there are about 4,500 people in the world with the name Kelsall. Details are provided here.
In counting populations it is necessary to consider which names are variant spellings of the name, resulting from the family spelling differently, illiteracy, or mistakes by the enumerator. Minor spelling differences are clearly variants of the same name, and there are additional clues from distribution by county. There are 36 Kellsall in 1881 and 35 in 1901, and 19 Kelsal in 1881 and 18 in 1901. I consider that these are clearly variants of Kelsall along with the less common Kelsale, Kelshall and Kalsall and are in effect the same name. On the other hand the name Kessell/Kessel was concentrated in Devon and Cornwall in 1881 where there were no Kelsall, and I think this is clearly a different name. I am uncertain about Kelshaw which had a population of 260 in 1881, mostly in Lancashire and Yorkshire. The relatively low incidence in Cheshire and Staffordshire combined with a high proportion in Yorkshire leads me to think that this name has a different origin. Data from 1881 are shown here.
Distribution in the UK
From various sources about half of all Kelsall households in the U.K. are in two counties, Staffordshire and Lancashire. About 70% are in four counties, Staffordshire, Lancashire, Cheshire and Yorkshire. This is consistent with the distribution seen in the census from 1841 to 1911 as shown here.
Distribution in the United States
From the website Whitepages, the state with the largest Kelsall population is Pennsylvania with 67 (16%) and about 50% live in 6 states: Pennsylvania, Colorado, New York, California, Illinois and Missouri. There is at least one person called Kelsall in 33 states. Pennsylvania also had the largest Kelsall population in 1880 and 1940. Details are provided here.
Historical Population Trends
Analysis of population growth is provided here.