Area code 573 is a telephone area code in the North American Numbering Plan that serves most of eastern and central Missouri outside the St. Louis and Kansas City metropolitan areas. It covers cities such as Columbia, Jefferson City, Cape Girardeau, Rolla, Farmington, and Poplar Bluff. The code was split from area code 314 on January 7, 1996, and today it overlays with area code 235 across the same territory.
How the 573 overlay actually works
The 573 region sits in eastern Missouri, stretching from the outskirts of St. Louis south to the Arkansas border and north toward the Iowa line. It surrounds but does not include St. Louis County, St. Charles County, or the city of St. Louis, which remain in area codes 314 and 636. It also excludes Kansas City and its suburbs in western Missouri, served by 816 and 913.
The underlying mechanism is the North American Numbering Plan, a 10-digit dialing system administered by the North American Numbering Plan Administrator under FCC oversight. Each area code holds a finite pool of seven-digit numbers. When a region's pool runs low, regulators either split the region into two codes or overlay a new code on the same territory. Missouri chose an overlay for 573.
An overlay means new numbers in the region may receive either 573 or the newer code, 235. Both codes describe the same geographic footprint. A caller cannot infer location from the specific code alone. The 235 overlay was approved because the 573 pool was projected to exhaust, and it preserves existing 573 numbers while adding capacity.
The counterintuitive detail: an overlay does not shorten or lengthen dialing for most people. Ten-digit dialing was already mandatory across the 573 region before 235 arrived, so the overlay added a code without changing how residents dial local calls. The visible change is that a new neighbor's number may start with 235 even though you live in the same town.
Plain-language version: 573 and 235 are two labels on the same map, and dialing ten digits is what makes either work.
Quantified context: population, geography, and number supply
The 573 region covers roughly the eastern half of Missouri outside the two major metros. Columbia, home to the University of Missouri, is the largest city in the code, with a population near 126,000. Jefferson City, the state capital, sits in the region at roughly 43,000 residents. Cape Girardeau, Rolla, Farmington, and Poplar Bluff anchor the southern and southeastern portions.
Missouri's total population is about 6.2 million. The St. Louis and Kansas City metros together account for well over half of that, which means the 573 territory holds a substantial share of the state's land area but a minority of its residents. Sparse population density is exactly why the code survived so long before needing relief.
Number pools are allocated in blocks of 10,000 by rate center, not by raw population. A rural county with few residents may still consume numbers inefficiently because carriers request blocks in fixed increments. That block-allocation rule, not population alone, drives exhaustion timelines. It explains why a low-density region can still run short.
Timeline of the 573 code
| Date | Event |
|---|---|
| Pre-1996 | Eastern Missouri outside St. Louis served by area code 314 |
| January 7, 1996 | Area code 573 split from 314 for outstate eastern Missouri |
| 1990s–2000s | Wireless growth and second lines accelerate number consumption |
| 2000s | Ten-digit dialing becomes standard practice across the region |
| 2023 | Regulators approve area code 235 as an overlay for 573 |
| 2025 | 235 overlay implementation proceeds as the 573 pool nears exhaustion |
The 1996 split itself was a response to the first wave of number exhaustion, driven by fax machines, pagers, and early cell phones. Each subsequent technology wave consumed another slice of the pool.
Edge cases and boundary confusion
Boundaries are the most common source of error. Communities near St. Louis sometimes assume they are in 573 when they are actually in 636 or 314. The line does not follow a simple ring; it follows rate-center boundaries that can jog around specific towns.
Another edge case involves numbers ported across codes. Wireless number portability, mandated since 2003, lets a customer keep a 573 number after moving to another state. A 573 prefix therefore does not guarantee the person is in Missouri. This is the professional caveat worth internalizing: area codes indicate where a number was issued, not where the phone is now.
Missouri also uses area code 660 in north-central Missouri and 417 in the southwest. Someone near the 573/660 line may misjudge which code applies to a given town. Checking a carrier's rate-center map or the official NANPA database resolves it.
Red flag: assuming a 573 number means the caller is local to you. Red flag: treating 235 as a different region rather than the same footprint. Red flag: dialing seven digits and expecting completion; ten-digit dialing is required. Red flag: relying on a prefix lookup tool for emergency or legal location purposes.
Common misconceptions
Misconception one: 573 is a St. Louis code. It is not. St. Louis is 314, and its suburbs are largely 636. The 573 region begins outside the metro boundary.
Misconception two: 235 replaced 573. It did not. An overlay adds capacity alongside the existing code. Existing 573 numbers stay valid.
Misconception three: area codes map precisely to city limits. They map to rate centers, which are regulatory constructs, not municipal boundaries.
Misconception four: a new area code means the old one is retired. Overlays exist precisely to avoid forced renumbering. The older code remains active indefinitely.
Plain-language version: a new code next door does not erase the old one; it just gives the region more room.
Practical actions
If you need to determine whether a number is in the 573 region, start with the NANPA area code database rather than a consumer lookup site, which may recycle stale data. For business records, store the full ten-digit number and the rate center, not just the area code.
If you are setting up a new line in the region, expect either a 573 or 235 assignment from your carrier. You generally cannot choose which; the carrier draws from its available blocks. If a specific code matters for branding, ask the carrier before ordering.
If you manage a call-routing system, update your tables to accept 235 as equivalent to 573 for the same geography. Failing to add the new code will drop legitimate calls.
For address verification or fraud screening, treat area code as a weak signal only. Cross-check with billing address, device location, or account history.
Limitations and what the code cannot tell you
An area code is a numbering artifact, not a geographic locator. It cannot confirm where a person is standing, whether a business is legitimate, or which jurisdiction applies to a dispute. Portability and VoIP have decoupled numbers from place more than at any point in the system's history.
Coverage maps also lag reality. Rate-center boundaries shift, and carrier allocations change without public fanfare. Any current statistic about pool exhaustion should be verified against NANPA's published relief planning documents rather than secondary sources.
This article is general educational information about telephone numbering, not legal, regulatory, or safety advice. For jurisdiction-specific questions, such as emergency dispatch location or legal service requirements, consult the relevant local authority or a qualified professional.