# St. Charles County, Missouri

St. Charles County is located in the central eastern part of the U.S. state of Missouri. As of the 2020 census, the population was 405,262, making it Missouri's third-most populous county. Its county seat is St. Charles. The county was organized October 1, 1812, and named for Saint Charles Borromeo, an Italian cardinal.
St. Charles County is part of the St. Louis, MO-IL Metropolitan Statistical Area and contains many of the city's northwestern suburbs. The wealthiest county in Missouri, St. Charles County is one of the nation's fastest-growing counties.
St. Charles County includes a part of the Augusta AVA, an area of vineyards and wineries designated by the federal government in 1980 as the first American Viticultural Area. The county's rural outer edge along the south-facing bluffs above the Missouri River, is also part of the broader Missouri Rhineland.

## History

The County of St. Charles was originally called the District of St. Charles and had no definite limits until 1816 to 1818 when neighboring counties were formed. The borders of St. Charles are the same today as they were in 1818.

## Geography

According to the U.S. Census Bureau, the county has a total area of 593 square miles (1,540 km$^2$), of which 560 square miles (1,500 km$^2$) is land and 32 square miles (83 km$^2$) (5.4%) is water.
The highest elevation is 901 feet (275 m) northwest of Augusta near Femme Osage Creek headwaters.

### Adjacent counties

* Lincoln County (northwest)
* Calhoun County, Illinois (north)
* Jersey County, Illinois (northeast)
* Madison County, Illinois (east)
* St. Louis County (southeast)
* Franklin County (south)
* Warren County (west)

### Major highways

* I-64 – Major freeway in the western portion of the county. Originally U.S. Route 40, the highway was upgraded to Interstate standards in the late 2000s. The highway was re-signed as Interstate 64 from the Daniel Boone Bridge to Interstate 70 in Wentzville in 2009.
* I-70 – The major east–west thoroughfare in the county. It is mostly a six-lane freeway in the county, but there are sections in St. Charles and St. Peters where the Interstate widens to 11 lanes of traffic.
* Interstate 70 Business
* US-40
* US-61
* US-67
* Rte-79
* Rte-94
* Rte-364 – A freeway in the southern and central portions of the county that begins at Interstate 270 in western St. Louis County and ends at Interstate 64 in Lake St. Louis.
* Rte-370 – A six-lane freeway that connects Interstate 70 in St. Charles County and Interstate 270 in St. Louis County.

### National protected area

* Two Rivers National Wildlife Refuge (part)

## Climate

Saint Charles County :
Climate chart (explanation) :

## Demographics

St. Charles County, Missouri – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race. :
| Race / Ethnicity (NH = Non-Hispanic) | Pop 2000 | Pop 2010 | Pop 2020 | % 2000 | % 2010 | % 2020 |
| White alone (NH) | 266,158 | 321,078 | 335,879 | 93.76% | 89.07% | 82.88% |
| Black or African American alone (NH) | 7,573 | 14,827 | 20,672 | 2.67% | 4.11% | 5.10% |
| Native American or Alaska Native alone (NH) | 596 | 692 | 623 | 0.21% | 0.19% | 0.15% |
| Asian alone (NH) | 2,397 | 7,789 | 11,068 | 0.84% | 2.16% | 2.73% |
| Pacific Islander alone (NH) | 61 | 153 | 199 | 0.02% | 0.04% | 0.05% |
| Other race alone (NH) | 224 | 427 | 1,377 | 0.08% | 0.12% | 0.34% |
| Mixed race or Multiracial (NH) | 2,698 | 5,536 | 19,433 | 0.95% | 1.54% | 4.80% |
| Hispanic or Latino (any race) | 4,176 | 9,983 | 16,011 | 1.47% | 2.77% | 3.95% |
| Total | 283,883 | 360,485 | 405,262 | 100.00% | 100.00% | 100.00% |

### 2020 census

As of 2020, there were 405,262 people and 150,668 households residing in the county. The population density was 643 inhabitants per square mile (248/km$^2$). There were 161,144 housing units. The racial makeup of the county was 83.8% White, 5.2% African American, 0.1% Native American, 2.8% Asian, 0.1% Pacific Islander, and 6.5% from two or more races. Hispanic or Latino made up 4.0% of the population.
There were 101,663 households, out of which 40.50% had children under the age of 18 living with them, 63.20% were married couples living together, 9.20% have a woman whose husband does not live with her, and 24.20% were non-families. 19.40% of all households were made up of individuals, and 5.90% had someone living alone who was 65 years of age or older. The average household size was 2.76 and the average family size was 3.18.
In the county, the population was spread out in age, with 29.00% under the age of 18, 8.20% from 18 to 24, 32.60% from 25 to 44, 21.60% from 45 to 64, and 8.80% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 97.10 males. For every 100 females age 18 and over, there were 94.10 males.
The median income for a household in the county was $71,458, and the median income for a family was $64,415. Males had a median income of $44,528 versus $29,405 for females. The per capita income for the county was $23,592. 4.00% of the population and 2.80% of families were below the poverty line. Out of the total people living in poverty, 4.90% are under the age of 18 and 5.10% are 65 or older.
St. Charles County has had one of the fastest-growing populations in the state for many decades, with 55% growth in the 1970s, 48% in the 1980s, 33% in the 1990s, and another 27% in the 2000s. The county sits at a cross-section of industry, as well as extensive retail and some agriculture. With the Missouri River on the south and east and the Mississippi River on the north, the county is bisected east to west by Interstate 70. After St. Charles Airport closed in 2010, the county has one remaining small airport, St. Charles County Smartt Airport. Two ferries cross the Mississippi River from St. Charles County.

## Education
### Public schools

School districts include:
* Fort Zumwalt R-II School District
* Francis Howell R-III School District
* Orchard Farm R-V School District
* St. Charles R-VI School District
* Washington School District
* Wentzville R-IV School District
High schools (all grades 9–12):
* Fort Zumwalt District
   * Fort Zumwalt East High School – St. Peters
   * Fort Zumwalt North High School – O'Fallon
   * Fort Zumwalt South High School – St. Peters
   * Fort Zumwalt West High School – O'Fallon
* Francis Howell District
   * Francis Howell Central High School – Cottleville
   * Francis Howell North High School – St. Peters
   * Francis Howell High School – Weldon Spring Heights
* Orchard Farm District
   * Orchard Farm High School – St. Charles
* St. Charles District
   * St. Charles High School – St. Charles
   * St. Charles West High School – St. Charles
* Wentzville District
   * Liberty High School – Lake St. Louis
   * Emil E. Holt High School – Wentzville
   * Timberland High School – Wentzville

### Private schools

* Academy of the Sacred Heart – St. Charles – (PK-08) – Roman Catholic
* All Saints School – St. Peters – (K-08) – Roman Catholic
* Assumption Catholic Grade School – O'Fallon – (K-08) – Roman Catholic
* Christian High School– O'Fallon and St. Peters– (PK-12) – Non-denominational Christian
* Duchesne High School– St. Charles– (09-12)– Roman Catholic
* First Baptist Christian Academy – O'Fallon – (PK-07) – Non-denominational Christian
* Foristell Baptist Academy – Foristell – (K-09) – Baptist
* Hope Montessori Academy – Lake St. Louis – (PK-K) – Nonsectarian
* Immaculate Conception Catholic School – Dardenne Prairie – (K-08) – Roman Catholic
* Immanuel Lutheran School – St. Charles – (PK-08) – Lutheran
* Immanuel Lutheran School – Wentzville – (PK-08) – Lutheran
* Liberty Classical School – O'Fallon – (07-12) – Non-denominational Christian
* Lutheran High School of St. Charles County – St. Peters – (09-12) – Lutheran
* Messiah Lutheran School – Weldon Spring – (PK-08) – Lutheran
* Mid Rivers Seventh-day Adventist School – St. Peters – (03-08) – Seventh-day Adventist
* St. Charles Borromeo – St. Charles – (K-08) – Roman Catholic
* St. Cletus School – St. Charles – (K-08) – Roman Catholic
* St. Dominic High School – O'Fallon – (09-12) – Roman Catholic
* St. Elizabeth St. Robert Regional School – St. Charles – (PK-08) – Roman Catholic
* St. Joseph School – Cottleville – (K-08) – Roman Catholic
* St. Joseph School – Wentzville – (PK-08) – Roman Catholic
* St. Patrick Elementary School – Wentzville – (K-08) – Roman Catholic
* St. Paul Elementary School – St. Paul – (PK-08) – Roman Catholic
* St. Peter Catholic School – St. Charles – (PK-08) – Roman Catholic
* St. Theodore School – Wentzville – (K-08) – Roman Catholic
* Sts. Joachim & Ann School – St. Charles – (PK-08) – Roman Catholic
* Trinity Lutheran School – St. Charles – (01-08) – Lutheran
* Willott Road Christian Academy – St. Peters – (NS-09) – Baptist
* Zion Lutheran School – St. Charles – (PK-08) – Lutheran

### Alternative schools

* Boonslick State School – St. Peters – Special Education
* Fort Zumwalt Hope High School – O'Fallon – Other/Alternative School – (09-12)
* Francis Howell Union High School – St. Charles – Other/Alternative School – (09-12)
* Heritage Landing – St. Peters – Other/Alternative School – (06-12)
* The Lead School – O'Fallon – Other/Alternative School – (K-12)
* Lewis & Clark Career Center – St. Charles – Vocational/Technical School – (09-12)
* Quest Day Treatment Center – St. Charles – Other/Alternative School – (06-12)
* Success Campus – St. Charles – Other/Alternative School – (09-12)

### Higher education

* Lindenwood University – St. Charles
* St. Charles Community College – Cottleville

### Public libraries

* St. Charles City-County Library District

## Government

St. Charles County is governed by a county executive and a county council. The county council consists of seven members, each elected from various districts in the county. The county executive is elected by the entire county. The current executive is Steve Ehlmann. He was preceded by Joe Ortwerth, who was preceded by Gene Schwendemann, the first county executive of St. Charles County under the new form of government. The executive under the old form of county government was termed a "judge." The county had 258,525 registered voters as of March 2016.
St. Charles County Ambulance District (SCCAD) is the largest such district in Missouri, serving all of St. Charles County and its population of nearly 370,000.

### Law enforcement

The St. Charles County Sheriff's Department (SCCSD) is responsible for court services and security, prisoner transport, civil process, and bailiffs. Until the end of 2014, SCCSD was the primary law enforcement agency serving unincorporated areas of St. Charles County. On January 1, 2015, the St. Charles County Police Department was established and assumed that responsibility. It should not be confused with the St. Charles City Police Department. The St. Charles County Regional SWAT Team is made up of officers from each county law enforcement agency.
The SCCPD Aviation Unit is part of a multi-jurisdictional unit known as the Metro Air Support Unit, with the Metropolitan Police Department, City of St. Louis; St. Louis County Police Department; and St. Charles County Police Department. As of 2024, the fleet included five helicopters, and twelve pilots or pilots in training.
In May 2022, Ryan Keuhner, who was then an SCCSD deputy, shot and killed his neighbor's 3-year-old rescue dog with a pellet gun. The shooting was reportedly unprovoked and Keuhner was off duty at the time. Video of the dog's owner confronting Keuhner was uploaded online, and later gained national coverage. Keuhner resigned in June 2022 and was charged with a class A misdemeanor for animal abuse.

### Library resolution

In 2023, the county council issued a resolution aimed at library policies and staff online activities. The resolution followed protests and comments at council meetings from residents who complained about a staff member wearing gender non-conforming clothes. Within the resolution, the council asked the library CEO to remove an article they shared on their personal LinkedIn profile related to conservative campaigns targeting public libraries and freedom of speech.

## Politics
### Local

The Republican Party predominantly controls politics at the local level in St. Charles County. Republicans hold all the elected positions in the county.
| Position | Incumbent | Party |
| Assessor | Travis Welge | Republican |
| Collector | Michelle McBride | Republican |
| Council Member – District 1 | Matt Swanson | Republican |
| Council Member – District 2 | Joseph Brazil | Republican |
| Council Member – District 3 | Michael Elam | Republican |
| Council Member – District 4 | David Hammond | Republican |
| Council Member – District 5 | Terry Hollander | Republican |
| Council Member – District 6 | Nancy Schneider | Republican |
| Council Member – District 7 | Tim Baker | Republican |
| County Executive | Steve Ehlmann | Republican |
| Director of Elections | Kurt Bahr | Republican |
| Prosecuting Attorney | Joe McCulloch | Republican |
| Recorder | Mary Dempsey | Republican |
| Sheriff | Scott Lewis | Republican |

### State

Past Gubernatorial Elections Results :
| Year | Republican | Democratic | Third Parties |
| 2024 | 59.43% 132,563 | 38.39% 85,628 | 2.18% 4,864 |
| 2020 | 58.12% 128,230 | 39.84% 87,888 | 2.04% 4,496 |
| 2016 | 54.52% 103,946 | 42.58% 85,704 | 2.90% 5,836 |
| 2012 | 48.58% 89,144 | 48.97% 89,860 | 2.45% 4,486 |
| 2008 | 44.51% 82,440 | 53.84% 99,705 | 1.65% 3,058 |
| 2004 | 55.90% 91,323 | 42.96% 70,184 | 1.14% 1,865 |
| 2000 | 58.24% 74,357 | 39.49% 50,415 | 2.27% 2,907 |
| 1996 | 49.48% 47,886 | 48.01% 46,462 | 2.50% 2,424 |
St. Charles County is divided among eleven legislative districts in the Missouri State House of Representatives, all of which are held by Republicans.
* District 63 – Tricia Byrnes (R-Wentzville, since 2023). Consists of most of Wentzville.
* District 64 – Tony Lovasco (R-O'Fallon, since 2019). Consists of Flint Hill, Josephville, St. Paul, and parts of Foristell, O'Fallon, and Wentzville.
* District 65 – Wendy Hausman (R-St. Peters, since 2023). Consists of West Alton, Portage Des Sioux, and parts of Cottleville, St. Charles, and St. Peters.
* District 69 – Adam Schnelting (R-St. Charles, since 2019). Consists of parts of St. Peters and Weldon Spring.
* District 102 – Richard West (R-Wentzville, since 2019). Consists of Augusta, Defiance, New Melle, Weldon Springs Heights, and parts of Cottleville, O'Fallon, St. Peters, and Weldon Spring.
* District 103 – Dave Hinman (R-O'Fallon, since 2023). Consists of part of O'Fallon.
* District 104 – Phil Christofanelli (R-St. Charles, since 2019). Consists of part of St. Charles and St. Peters.
* District 105 – Adam Schwadron (R-St. Charles, since 2021). Consists of part of St. Charles.
* District 106 – Travis Wilson (R-St. Charles, since 2023). Consists of part of St. Charles.
* District 107 – Mark Matthiesen (R-O'Fallon, since 2023). Consists of parts of Dardenne Prairie and O'Fallon.
* District 108 – Justin Hicks (R-Lake St. Louis, since 2023). Consists of Lake St. Louis and parts of Dardenne Prairie and O'Fallon.
St. Charles County is divided into three districts in the Missouri State Senate, each of which are represented by Republicans.
* District 2 – Nick Schroer (R-Defiance, since 2023). Consists of the communities of Augusta, Cottleville, Dardenne Prairie, Defiance, Josephville, Lake St. Louis, New Melle, O'Fallon, St. Paul, Weldon Spring, and Weldon Spring Heights.
* District 10 - Travis Fitzwater (R-New Bloomfield, since 2023). Consists of the communities of Flint Hill, Foristell, and Wentzville.
* District 23 – Bill Eigel (R-Weldon Spring, since 2017). Consists of Portage Des Sioux, St. Charles, St. Peters, and West Alton.

### Federal

Missouri is represented in the U.S. Senate by Josh Hawley and Eric Schmitt, whose most recent election results from the county are included here.
U.S. Senate — Missouri — (2022) :
| Party | Party | Candidate | Votes | % |
| | Republican | Eric Schmitt | 83,559 | 55.35% |
| | Democratic | Trudy Busch Valentine | 64,552 | 42.76% |
| | Libertarian | Jonathan Dine | 2,158 | 1.43% |
| | Constitution | Paul Venable | 709 | 0.47% |
| Total votes | Total votes | Total votes | 150,978 | 100.00% |
U.S. Senate — Missouri — (2018) :
| Party | Party | Candidate | Votes | % |
| | Republican | Josh Hawley | 93,172 | 52.90% |
| | Democratic | Claire McCaskill | 77,973 | 44.30% |
| | Independent | Craig O'Dear | 2,393 | 1.40% |
| | Libertarian | Japheth Campbell | 1,836 | 1.0% |
| | Green | Jo Crain | 731 | 0.4% |
| Total votes | Total votes | Total votes | 176,105 | 100% |
U.S. Senate — Missouri — (2016) :
| Party | Candidate | Votes | % | ±% |
| Republican | Roy Blunt | 103,946 | 51.78% | +6.87 |
| Democratic | Jason Kander | 88,238 | 43.95% | −5.18 |
| Libertarian | Jonathan Dine | 5,238 | 2.61% | −3.35 |
| Green | Johnathan McFarland | 1,970 | 0.98% | +0.98 |
| Constitution | Fred Ryman | 1,355 | 0.67% | +0.67 |
U.S. Senate — Missouri — (2012) :
| Party | Candidate | Votes | % |
| Democratic | Claire McCaskill | 89,993 | 49.10% |
| Republican | Todd Akin | 82,278 | 44.90% |
| Libertarian | Jonathan Dine | 10,924 | 6.0% |
U.S. Senate — Missouri — (2010) :
| Party | Candidate | Votes | % |
| Republican | Roy Blunt | 73,695 | 59.09% |
| Democratic | Robin Carnahan | 43,955 | 35.24% |
| Libertarian | Jonathan Dine | 10,924 | 6.0% |
Part of St. Charles County is included in Missouri's 2nd Congressional District and is currently represented by Ann Wagner in the U.S. House of Representatives.
U.S. House of Representatives — Missouri's 2nd Congressional District — St. Charles County (2020) :
| Party | Candidate | Votes | % |
| Republican | Ann Wagner | 45,941 | 57.38% |
| Democratic | Jill Schupp | 31,239 | 39.02% |
| Libertarian | Martin Schulte | 2,821 | 3.52% |
U.S. House of Representatives — Missouri's 2nd Congressional District — St. Charles County (2018) :
| Party | Party | Candidate | Votes | % |
| | Republican | Ann Wagner | 37,875 | 57.5% |
| | Democratic | Cort VanOstran | 26,782 | 40.6% |
| | Libertarian | Tony Kirk | 956 | 1.5% |
| | Green | David Arnold | 304 | 0.5% |
| | Independent | Ken Newhouse (write-in) | 0 | 0.0% |
| Total votes | Total votes | Total votes | 65,917 | 100.0% |
| | Republican hold | Republican hold | Republican hold | Republican hold |
Most of St. Charles County is included in Missouri's 3rd Congressional District and is currently represented by Blaine Luetkemeyer (R-St. Elizabeth) in the U.S. House of Representatives.
U.S. House of Representatives — Missouri's 3rd Congressional District — St. Charles County (2020) :
| Party | Candidate | Votes | % |
| Republican | Blaine Luetkemeyer | 84,071 | 61.74% |
| Democratic | Megan Rezabek | 49,315 | 36.22% |
| Libertarian | Leonard J Steinman II | 2,631 | 1.93% |
U.S. House of Representatives — Missouri's 3rd Congressional District — St. Charles County (2018) :
| Party | Party | Candidate | Votes | % |
| | Republican | Blaine Luetkemeyer | 61,751 | 57.77% |
| | Democratic | Katy Geppert | 43,070 | 40.30% |
| | Libertarian | Donald V. Stolle | 2,062 | 1.93% |
| Total votes | Total votes | Total votes | 106,883 | 100.0% |
| | Republican hold | Republican hold | Republican hold | Republican hold |
United States presidential election results for St. Charles County, Missouri :
| Year | Republican | Republican | Democratic | Democratic | Third party(ies) | Third party(ies) |
| Year | No. | % | No. | % | No. | % |
| 2024 | 130,588 | 57.42% | 92,226 | 40.56% | 4,594 | 2.02% |
| 2020 | 128,389 | 57.69% | 89,530 | 40.23% | 4,647 | 2.09% |
| 2016 | 121,650 | 59.87% | 68,626 | 33.78% | 12,908 | 6.35% |
| 2012 | 110,784 | 59.44% | 71,838 | 38.55% | 3,744 | 2.01% |
| 2008 | 102,550 | 54.27% | 84,183 | 44.55% | 2,224 | 1.18% |
| 2004 | 95,826 | 58.61% | 66,855 | 40.89% | 807 | 0.49% |
| 2000 | 72,114 | 56.04% | 53,806 | 41.81% | 2,766 | 2.15% |
| 1996 | 47,705 | 46.66% | 41,369 | 40.46% | 13,172 | 12.88% |
| 1992 | 38,673 | 36.29% | 37,263 | 34.97% | 30,627 | 28.74% |
| 1988 | 50,005 | 62.90% | 29,286 | 36.84% | 209 | 0.26% |
| 1984 | 47,784 | 73.06% | 17,617 | 26.94% | 0 | 0.00% |
| 1980 | 36,050 | 60.32% | 20,668 | 34.58% | 3,050 | 5.10% |
| 1976 | 26,105 | 53.60% | 22,063 | 45.30% | 536 | 1.10% |
| 1972 | 25,677 | 69.94% | 11,034 | 30.06% | 0 | 0.00% |
| 1968 | 13,533 | 45.63% | 10,374 | 34.98% | 5,752 | 19.39% |
| 1964 | 9,020 | 38.30% | 14,530 | 61.70% | 0 | 0.00% |
| 1960 | 10,888 | 47.80% | 11,890 | 52.20% | 0 | 0.00% |
| 1956 | 9,462 | 55.40% | 7,618 | 44.60% | 0 | 0.00% |
| 1952 | 8,451 | 56.48% | 6,493 | 43.39% | 20 | 0.13% |
| 1948 | 5,976 | 49.54% | 6,049 | 50.14% | 39 | 0.32% |
| 1944 | 7,050 | 58.92% | 4,880 | 40.78% | 36 | 0.30% |
| 1940 | 7,792 | 59.14% | 5,334 | 40.48% | 50 | 0.38% |
| 1936 | 5,156 | 42.72% | 5,903 | 48.91% | 1,009 | 8.36% |
| 1932 | 3,664 | 34.12% | 6,911 | 64.37% | 162 | 1.51% |
| 1928 | 5,404 | 51.43% | 5,081 | 48.36% | 22 | 0.21% |
| 1924 | 4,668 | 59.11% | 2,364 | 29.94% | 865 | 10.95% |
| 1920 | 6,645 | 72.13% | 2,472 | 26.83% | 96 | 1.04% |
| 1916 | 3,518 | 64.16% | 1,914 | 34.91% | 51 | 0.93% |
| 1912 | 2,350 | 49.00% | 1,792 | 37.36% | 654 | 13.64% |
| 1908 | 3,480 | 62.84% | 1,979 | 35.73% | 79 | 1.43% |
| 1904 | 3,203 | 62.91% | 1,788 | 35.12% | 100 | 1.96% |
| 1900 | 3,324 | 58.10% | 2,343 | 40.95% | 54 | 0.94% |
| 1896 | 3,173 | 56.15% | 2,448 | 43.32% | 30 | 0.53% |
| 1892 | 2,522 | 50.00% | 2,485 | 49.27% | 37 | 0.73% |
| 1888 | 2,668 | 52.65% | 2,381 | 46.99% | 18 | 0.36% |

### Federal politics

St. Charles County has long been a Republican stronghold. Despite this, it did vote for Medicaid expansion in 2020 and legal abortion in 2024. It was also one of the few counties in Missouri to shift towards the Democrats from 2020 to 2024.

#### 2016 Missouri presidential primary results

Republican
Donald Trump won the most votes in St. Charles County, with 41.50 percent. U.S. Senator Ted Cruz (R-Texas) came in second with 38.87 percent, Governor John Kasich (R-Ohio) placed third with 10.70 percent, and U.S. Senator Marco Rubio (R-Florida) was fourth with 7.10 percent.
Democratic
U.S. Senator Bernie Sanders (I-Vermont) won the primary with 54.32 percent to former Secretary of State Hillary Clinton's 44.80 percent.

#### 2012 Missouri presidential primary results

Republican
Former U.S. Senator Rick Santorum (R-Pennsylvania) won the most votes in St. Charles County, with 56.29 percent. Former Governor Mitt Romney (R-Massachusetts) came in second with 25.43 percent, and former U.S. Representative Ron Paul (R-Texas) was third with 12.69 percent.
Democratic
With incumbent President Barack Obama facing no serious opposition, few St. Charles County voters voted in the Democratic primary; Obama won 87.83 percent.

#### 2008 Missouri presidential primary results

Republican
Former Governor Mitt Romney (R-Massachusetts) won the most votes in St. Charles County, with 37.72 percent. U.S. Senator John McCain (R-Arizona) came in second with 34.95 percent, former Governor Mike Huckabee (R-Arkansas) placed third with 21.83 percent, and U.S. Representative Ron Paul (R-Texas) was fourth with 3.83 percent.
Democratic
Former U.S. Senator Hillary Clinton (D-New York) received a total of 23,611 votes, more than any candidate from either party in St. Charles County during the 2008 presidential primary.

## Communities
### Cities

* Augusta
* Cottleville
* Dardenne Prairie
* Flint Hill
* Foristell
* Lake St. Louis
* New Melle
* O'Fallon
* Portage Des Sioux
* St. Charles (county seat)
* St. Paul
* St. Peters
* Weldon Spring
* Wentzville
* West Alton

### Villages

* Josephville
* Weldon Spring Heights

### Census-designated place

* Defiance

### Other unincorporated places

* Black Walnut
* Blase
* Boschertown
* Cappeln
* Elm Point
* Enon
* Femme Osage
* Gilmore
* Harvester
* Howell
* Kampville
* Klondike
* Marais Croche
* Matson
* Mechanicsville
* Nona
* Orchard Farm
* Pauldingville
* Peruque
* Schluersburg
* Toonerville
* Whitecorn

### Islands

* Apple Island
* Dresser Island
* Ellis Island
* Howell Island
* Two Branch Island

## Subregions
### Westplex

Westplex is an area within St. Charles County in east-central Missouri to the west of St. Louis County.
The Westplex is part of St. Charles County that used to be called "The Golden Triangle". The "triangle" was formed by I-70 to the north, Missouri Route 94 to the southeast, and I-64 to the southwest. Since almost all of the growth in St. Charles County was within this triangle it was dubbed the "Golden" area of St. Charles county, hence, Golden Triangle. Today the Westplex is made up of St. Charles, St. Peters, Weldon Spring, Cottleville, Dardenne Prairie, O'Fallon, Lake St. Louis, and Wentzville.