This was largely because the survey excluded all journeys of less than one mile.
From the newscientist.com
The United States adopted this international mile for most purposes, but retained the pre-1959 mile for some land-survey data, terming it the US survey mile.
From the en.wikipedia.org
From then its only utility has been land survey, before it was the standard mile.
From the en.wikipedia.org
Survey blocks cover quarter-mile-square areas with wetlands draining into the Rouge River.
From the freep.com
This year's survey showed 41 deer per square mile at the parks.
From the freep.com
An aerial survey along a 30-mile stretch of beach recently counted only 200 grebe, compared with the past population of 4,000 to 7,000.
From the time.com
Starting in 2002, the survey has biologists running the same 20-mile routes year after year.
From the kansas.com
When the birds are in Texas, they normally survey a square-mile area on foot for crabs, berries, acorns, worms and insects.
From the huffingtonpost.com
A 2005 population survey recorded as many as 80 deer per square mile.