Mercer County
Pennsylvania · County seat: Mercer · Active county or equivalent
FIPS code 42085 is Mercer County, Pennsylvania. With a population of 110,600 (2022 ACS estimate), it ranks #30 in Pennsylvania and #553 nationally. Mercer County is part of the Hermitage, PA. The state FIPS code for Pennsylvania is 42. This code is used in Census Bureau, BLS, EPA, HUD, and USDA federal datasets to identify this county.
County FIPS
42085
Population
110,600
2022 ACS · #553 nationally
Density
164.4/mi²
people per sq mile
Land Area
673
sq miles
Urban/Rural
Nonmetro — urban 20K+, adjacent to metro
RUCC 4
How This FIPS Code Works
The 5-digit FIPS code 42085 is formed by combining the 2-digit state identifier 42 (Pennsylvania) with the 3-digit county identifier 085. Together they uniquely identify Mercer County in every US federal dataset. No two counties share the same 5-digit FIPS code.
Census ACS Data for FIPS 42085
From the 2022 ACS 5-year estimates — the same values you'd retrieve by querying the Census API with county FIPS 42085.
Median Household Income
$57,353
ACS B19013_001E
Poverty Rate
13.5%
ACS B17001 (below poverty level)
Median Age
45.0
ACS B01002_001E
Metropolitan Area
Adjacent Counties (6)
Counties that share a border with Mercer County. Useful for regional analysis — these are the geographies you'd typically include when studying labor markets, commuting zones, or environmental spillovers around FIPS 42085.
Federal Datasets Using Code 42085
FIPS code 42085 appears as the county identifier in the following federal datasets. Analysts joining data across these sources use this code as the common geographic key.
Using FIPS Code 42085 in Code
Common patterns for querying federal datasets by this county's FIPS code. The leading zeros are significant — always treat FIPS codes as strings, not integers.
import requests
url = "https://api.census.gov/data/2022/acs/acs5"
params = {
"get": "NAME,B19013_001E,B01003_001E",
"for": "county:085",
"in": "state:42",
"key": "YOUR_CENSUS_API_KEY",
}
r = requests.get(url, params=params)
data = r.json() # [[header...], [Mercer County, Pennsylvania, income, pop, ...]-- 5-digit combined FIPS (state + county)
SELECT * FROM your_table WHERE county_fips = '42085';
-- Some datasets store state and county separately
SELECT * FROM your_table
WHERE state_fips = '42'
AND county_fips = '085';
-- ⚠ Never cast to integer — leading zeros are lost:
-- county_fips = 42085 is WRONG for this countylibrary(tidycensus)
get_acs(
geography = "county",
variables = c(income = "B19013_001E", pop = "B01003_001E"),
state = "42",
county = "085",
year = 2022
)ZIP Codes in Mercer County
ZIP codes do not align perfectly with county boundaries — a single ZIP code can span multiple counties, and a county can contain parts of many ZIP codes. The ratios below (from the Census 2020 ZCTA relationship file) show the land area share of each ZCTA that falls within Mercer County. Why FIPS ≠ ZIP →
| ZIP Code | % in county |
|---|---|
| 16151 | 100.0% |
| 16154 | 100.0% |
| 16145 | 100.0% |
| 16146 | 100.0% |
| 16148 | 100.0% |
| 16150 | 100.0% |
| 16113 | 100.0% |
| 16114 | 100.0% |
| 16121 | 100.0% |
| 16124 | 100.0% |
| 16130 | 100.0% |
| 16133 | 100.0% |
| 16161 | 100.0% |
| 16137 | 100.0% |
| 16125 | 98.4% |
| 16311 | 95.4% |
| 16127 | 90.0% |
| 16159 | 89.5% |
| 16153 | 86.5% |
| 16142 | 62.4% |
| 16134 | 46.0% |
| 16143 | 29.3% |
| 16110 | 24.0% |
| 16156 | 21.4% |
| 16314 | 11.4% |
| 16362 | 11.3% |
| 16342 | 3.4% |
| 16057 | 1.1% |