Zip codes crossing state lines can be a source of confusion for many. Understanding which codes span across states is crucial for businesses, logistics, and even personal correspondences.
This article addresses the specific zip codes that cross state boundaries, detailing the regions they cover and the implications for residents and businesses.
Zip Codes and State Boundaries
Zip codes are typically associated with specific states, but there are some limited exceptions. The first digit of a zip code usually indicates a group of states, while the following digits narrow it down to more specific locations.
However, full zip codes don't strictly adhere to state or county lines. They can cross state lines and span multiple counties, cities, or even congressional districts. Unsurprisingly, this can cause trouble and confusion in certain industries.
For example, Fort Campbell's zip code 42223 covers areas in both Kentucky and Tennessee. The sectional center facility (SCF) codes also demonstrate this flexibility.
An SCF is a mail sorting center that can serve areas across state lines, such as the 739 code in Oklahoma being used for parts of Texas.
First Digit Zip Code Table
The chart below shows the list of states the first number of a zip code covers. As you can see, some numbers cover a much larger area than others.
| First Digit | States/Territories Covered |
|---|---|
| 0 | CT, MA, ME, NH, NJ, NY (Fishers Island only), PR, RI, VT, VI, APO AE, FPO AE |
| 1 | DE, NY, PA |
| 2 | DC, MD, NC, SC, VA, WV |
| 3 | AL, FL, GA, MS, TN, APO AA, FPO AA |
| 4 | IN, KY, MI, OH |
| 5 | IA, MN, MT, ND, SD, WI |
| 6 | IL, KS, MO, NE |
| 7 | AR, LA, OK, TX |
| 8 | AZ, CO, ID, NM, NV, UT, WY |
| 9 | AK, AS, CA, GU, HI, MH, FM, MP, OR, PW, WA, APO AP, FPO AP |
Full Zip Codes that Cross State Lines in the US
There are 13 multi-state US Census ZIP Code Tabulation Areas (ZCTAs) that cross state lines. They are shown below:
- 02861: Massachusetts, Rhode Island
- 42223: Kentucky, Tennessee
- 59221: Montana, North Dakota
- 63673: Illinois, Missouri
- 71749: Arkansas, Louisiana
- 73949: Oklahoma, Texas
- 81137: Colorado, New Mexico
- 84536: Arizona, Utah
- 86044: Arizona, Utah
- 86515: Arizona, New Mexico
- 88063: New Mexico, Texas
- 89439: California, Nevada
- 97635: California, Oregon
Regulations Governing Zip Code Boundaries
Zip code boundaries are determined by the United States Postal Service (USPS) based on the efficiency of mail delivery routes and geographical considerations. There are no strict laws that prevent zip codes from crossing state lines.
Though as you've seen from the table above, it's very rare for the full zip code to cross a state boundary. Out of around 41k zip codes, only around 13 cross the state lines. It seems that the USPS tries their best to make zip code boundaries conform to the state boundary.
Implications of Zip Codes Crossing State Lines
For residents and businesses, having a zip code that crosses state lines can lead to confusion in services like emergency response, taxation, and school districting. Governments may face challenges in administration and data collection.
Impacts on Postal Services
Crossing state lines can complicate mail delivery and sorting operations. Postal workers must be familiar with the overlapping regions, which can increase the potential for delivery errors and delays.