Total enrollment
73,667
-5,135 (-7%) vs SY 2020-21
Jefferson County
Colorado · Public K-12
Jefferson County runs 168 public K-12 schools per the latest NCES counts, with an average school size of about 445 students. By level, that breaks down as 90 elementary, 21 middle, and 32 high schools.
4-year change in Jefferson County
SY 2020-21 vs SY 2024-25School count
145
-14 (-9%) vs SY 2020-21
Source: NCES Common Core of Data, enrollment-weighted demographic averages
How Jefferson County ranks
Among counties| Measure | This county | In Colorado | In the US |
|---|---|---|---|
| State test proficiency ranked highest first | 43.7% | #8 of 34 | N/A |
| Enrollment ranked largest first | 74,739 | #5 of 41 | #139 of 2,745 |
| Number of schools ranked most first | 148 | #5 of 41 | N/A |
| Students per teacher ranked fewest first | 16.8:1 | #33 of 41 | #2,250 of 2,655 |
| Free or reduced-price lunch share ranked highest first | 32.0% | #37 of 41 | #2,354 of 2,526 |
| Diversity index ranked most diverse first | 51.7% | #19 of 40 | #1,017 of 2,707 |
Counties need at least 3 schools and 1,000 students to be ranked. Test proficiency is ranked within the state only, since each state gives a different test. Each rank links to the full list.
Jefferson County school rankings
Residents
579,377
all ages · ACS 5-yr
Schools
168
3 districts
Enrollment
74,739
students · NCES CCD
Median income
$110,656
Above Colorado avg
Free/reduced lunch
32.0%
Below Colorado avg
Elementary
90
35,962 students
Middle
21
11,451 students
High
32
24,727 students
Combined / other
25
2,599 students
LARGEST DISTRICT
Jefferson County School District No. R-1
73,908 students · 3 districts in Jefferson County
County vs. school enrollment demographics
Left bar is the racial makeup of Jefferson County residents (Census ACS 5-year). Right bar is the enrollment-weighted makeup of public schools in the county (NCES CCD). NCES systematically under-reports Hispanic, Pacific Islander, and Native American enrollment for many schools; where the resident share is meaningful but the reported school share is zero, we mark the school bar "not reported".
County residents
School enrollment
Bachelor's+
52.0%
adults 25+
Poverty rate
3.6%
ACS 5-year
Unemployment
3.9%
civilian labor
Median age
41
18.5% under 18
Test scores in Jefferson County
Latest 2024-25 ELA proficiency, 115 schools ranked. Colorado state average: 44.9%.
Top 5 schools (ELA)
- Dennison Elementary School· 90.5%
- Parmalee Elementary School· 84.7%
- Kyffin Elementary School· 81.2%
- Mitchell Elementary School· 79.2%
- Ralston Elementary School· 79.2%
Lowest 5 schools (ELA)
- Prospect Academy· 5.0%
- Lumberg Elementary School· 9.0%
- Deane Elementary School· 12.4%
- Jefferson Junior/Senior High School· 14.0%
- Swanson Elementary School· 14.0%
Cities in Jefferson County
About Jefferson County
Jefferson County is a wide-reaching county of about 579,377 residents in Colorado. Its public-school system hosts approximately 74,739 students across 168 schools.
Stepping back, census numbers show the median household earns about $110,656 a year, 52% of adults hold a bachelor's degree or higher, and the poverty rate is around 4%. That income level is 43% noticeably above the Colorado median.
On the school-mix side, Jefferson County consists of 90 elementary schools (35,962 students), 21 middle schools (11,451), 32 high schools (24,727), and 25 combined or other schools.
The largest single district in Jefferson County is Jefferson County School District No. R-1, which alone enrolls about 73,908 students.
Over the past 4-year window. Combined enrollment now sits at 73,667 students, shrank 7% from the 78,802 reported in SY 2020-21. The school count fell from 159 to 145 across the same 4-year window.
Within the allk12 community for this area, the community for Jefferson County discusses sports rivalries, cross-district programs, and shared facilities. Discussions cut across districts, schools, and grade levels.
Frequently asked questions
DATA · Census ACS 5-year · NCES Common Core of Data