In many communities across the U.S., ZIP codes are a mark of identity. But in others, they are a source of confusion and consternation.
Since 2018, the City of Castle Pines has been attempting to change its ZIP code. Castle Pines, which incorporated in 2008, sits across two different ZIP code boundary areas: 80108, which expands into neighboring Castle Rock and Parker, and 80134, which is also shared with Parker.
ZIP codes, or Zone Improvement Plan codes, were invented in 1963 by the U.S. Postal Service as part of a system to improve the speed of mail delivery, according to the Library of Congress. Since then, the use of ZIP codes has expanded into areas far beyond mail delivery.
Because Castle Pines’ ZIP codes overlap local jurisdictions, figuring out where to remit local sales taxes can be confusing for retailers, said City Manager Michael Penny. This confusion arises from the fact that ZIP codes determine the city used in an address, according to a 2021 letter from Castle Pines to the USPS
“Even if a home or business is within Castle Pines’ city limits, its mailing address may appear to be in a neighboring city,” the letter said.
“When someone wants to buy from Amazon and they type their address in for their mailing address and it comes up and says ‘Castle Rock’ not ‘Castle Pines,’ you immediately have that confusion of where that sales tax needs to be remitted to,” said Mayor Tracy Engerman. “If we had our own ZIP code… it immediately then tells the retailer that they need to submit the sales tax to Castle Pines regardless of if it says ‘Castle Rock’ as the city on their address.”
Sales taxes are important because they are the main source of revenue for the city, former Mayor Tera Radloff said.