When the United States census packets were delivered to Oak Park earlier this month, some residents noticed that the envelopes contained the address, Agoura Hills.

Although Oak Park’s 91377 ZIP code was typed on the envelope, the name “Oak Park” was not. The error, coming from the Census Bureau, proved disconcerting.

“My question is, are they looking at 91377 as a second ZIP code of Agoura Hills or are they treating Oak Park as part of Ventura County, as it should be?” said Mike Green, chair of the Oak Park Municipal Advisory Council.

In an effort to prevent similar cases of confusion regarding insurance and other matters, Oak Park split from Agoura Hills and received its own ZIP code in 1999.

Green and others are concerned that the census information might not be credited to the right county and community. The information is used to establish legislative districts and the number of seats each state has in the House of Representatives. It also helps determine the allocation of $400 billion in federal funding for local public health, education, transportation and neighborhood projects.

But regardless of the city listed on the address, the data will still be applied correctly, said Sandra Hernandez, a media spokesperson from the Los Angeles regional census office in Northridge.

According to Hernandez, the reason “Agoura Hills” appears on the envelopes is that it makes it easier for postal workers to complete their sorting process. A bar code on the back of the return envelopes contains detailed information about the home that the envelope is returned from, she said.

“It’s almost like DNA. It’s a number that, when they punch it up, they will know what tract, what address, what city, what county it’s coming from,” Hernandez said.

Last year, census staff went into the communities to verify maps and addresses. In addition, local governments were asked to review the addresses in their communities and provide feedback.

“People shouldn’t really worry about the money not going to their neighborhoods because when they first got the questionnaire it didn’t say the city they identify with,” Hernandez said. “It’s not like Oak Park or any other neighborhood is going to get lost out there. The census will know that this is Oak Park.”