We estimate the amount of
37
Ar
produced in natural xenon via cosmic-ray-induced spallation, an inevitable consequence of the transportation and storage of xenon on the Earth’s surface. We then calculate the resulting
37
Ar
concentration in a 10-tonne payload (similar to that of the LUX-ZEPLIN experiment) assuming a representative schedule of xenon purification, storage, and delivery to the underground facility. Using the spallation model by Silberberg and Tsao, the sea-level production rate of
37
Ar
in natural xenon is estimated to be
0.024
 
 
atoms
/
kg
/
day
. Assuming the xenon is successively purified to remove radioactive contaminants in 1-tonne batches at a rate of
1
 
 
tonne
/
month
, the average
37
Ar
activity after 10 tons are purified and transported underground is
0.058
−
0.090
 
 
μ
Bq
/
kg
, depending on the degree of argon removal during above-ground purification. Such cosmogenic
37
Ar
will appear as a noticeable background in the early science data, while decaying with a 35-day half-life. This newly noticed production mechanism of
37
Ar
should be considered when planning for future liquid-xenon-based experiments.