ZIP code profile · 2024 county data

ZIP Code 63121

St. Louis County, Missouri: Census demographics for this ZIP plus the containing county's FBI UCR crime rate.

Data updated 2026-08-24

601
Property rate /100K (county)
24,126
Population (ZIP)
190
Violent rate /100K (county)

Is ZIP code 63121 safe? Honest data snapshot

ZIP code 63121 sits within St. Louis County, MO, a county whose reported crime runs below the national average (see the county-level FBI figures below, not a ZIP-specific calculation).

St. Louis County's reported crime sits somewhat below the national average: 190 violent and 601 property incidents per 100,000 residents in 2024.

ZIP 63121 carries a Census-reported population of 24,126, ranking #19 of 62 ZIPs in St. Louis County, spread across 6.77 square miles (about 3,564 people per square mile). For a full breakdown of St. Louis County's crime categories and year-over-year trend, see the St. Louis County crime page linked below.

ZIP 63121 has no FBI-native crime rate (postal codes are not police jurisdictions). The property-led county proxy above is from St. Louis County agency submissions; see methodology for the ZCTA plurality map. Methodology.

ZIP 63121 Census context

These are ZIP/ZCTA demographic estimates, separate from the county-level FBI proxy above. They describe the local settlement, not a crime rate.

Median household income
$39,668
Median age
38.3 years
Owner-occupied homes
51%
Occupied homes
11,204

Source: U.S. Census Bureau, ACS 2022 5-year ZCTA estimates (income, age, and occupied housing tenure).

How useful is the county proxy for ZIP 63121?

Within the participating-agency records for St. Louis County, reported violent and property crime rates both sit below their U.S. benchmarks: violent crime is 46% below and property crime is 65% below. The two submitted measures point in the same direction, but they do not establish complete county coverage or turn the result into a ZIP-level rating for 63121. Both comparisons use the same 2024 county reporting population and FBI-submitted counts, so the two directions are internally comparable for this release, not evidence about a different year.

63121 is a densely settled part of the county at about 3,564 people per square mile. Density is not a crime predictor on its own; it only shows why a county-wide average can conceal a very different local setting inside this ZIP.

St. Louis County UCR book ZIP 63121 inherits

ZIP 63121 itself is about 3,564 people per Census sq mi across 6.8 sq mi (24,126 residents), a postal settlement fact independent of the county UCR proxy.

ZIP 63121 accounts for roughly 2.4% of the county reporting population (24,126 of 1,004,125).

St. Louis County leans on larceny-theft at 47% of reported offenses (mix index 3,061). ZIP 63121 has no separate FBI offense book.

St. Louis County offense mix (2024)

Mix index is HHI × 10,000 on county offense-type shares. Distinct from the per-100K rates in the hero; still county-agency data, not a ZIP-native FBI table.

Nationwide peers for ZIP 63121

Similar county violent rate (~190/100K)

Similar Census population (~24,126)

County detail: St. Louis County · State atlas: Missouri

Sources: U.S. Census Bureau (ZIP population, land area, 2020 ZCTA-to-county relationship file, ACS 5-year estimates) and FBI Uniform Crime Reporting (UCR) Program, Crime in the United States (CIUS) Table 10 (county-level crime, attributed via ZIP-to-county crosswalk).

Verify with Census.gov Geography and FBI.gov UCR.

Read our methodology , how this data is sourced, computed, and verified.

Every figure on PlainCrime is rendered directly from FBI Uniform Crime Reporting (UCR) source data, no number is typed in by an editor. This page combines Census ZIP-level figures with a ZIP-to-county crosswalk to attribute FBI UCR crime data honestly, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.