Evan from Philadelphia gave $46.75 (£29) to City Kitties back in 2009. He donated $86 (£53) in 2010, $97 (£60) in 2011 and $110 (£68) in 2012.
The boy accompanies his donations with a handwritten letter - the most recent of which was dated December 15, 2012.
"I hope that you guys have had a great year 2012!" Evan wrote. "I will keep donating to help save abandoned kittens from danger."
His latest contribution of $110 was matched by his parents, meaning City Kitties received $220 (£136) from the family last month.
Evan has also adopted a cat from the same local rescue in the past.
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