Cahokia

Park Pre-Columbian Mississippian mound complex near St. Louis

Near St. Louis, Cahokia Mounds preserves the earthworks of a pre-Columbian Mississippian city: Monk’s Mound, burial mounds, and an interpretive center. Archaeology trails and seasonal programs draw students, researchers, and visitors interested in indigenous North American history.

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Cahokia Mounds is a large pre-Columbian archaeological complex in southern Illinois near the modern city of Collinsville, representing the largest Mississippian period urban centre north of Mexico. The site’s earthen mounds and plaza complex document a densely inhabited, planned cityscape that flourished in the late first millennium and early second millennium CE.

The site’s most prominent feature is Monks Mound, a multi-terraced earthen pyramid rising about 30 meters and forming the ceremonial and political core of the site. Surrounding it are dozens of smaller platform mounds, a large central plaza, residential areas, and evidence of craft and food-preparation zones; a timber circle called Woodhenge has been reconstructed for interpretation.

Scholarly studies indicate the city reached its peak between about 1050 and 1350 CE, supporting a population that archaeological estimates place in the thousands to tens of thousands. The scale of earthworks and urban planning make Cahokia a key reference for understanding complex societies in precontact North America.

Cahokia Mounds State Historic Site lies on the east side of the Mississippi River, about 10 kilometers east of downtown St. Louis, and is managed as a protected archaeological park with trails, an interpretive centre and preserved mound complexes.

  • Peak population: Peak occupation occurred roughly between 1050 and 1350 CE, when the site supported a large, dense urban population estimated at up to about 20,000 people.
  • UNESCO status: Designated a UNESCO World Heritage Site for its significance as the largest precontact urban centre north of Mexico and for its preserved earthworks.

What to See #

  • Monks Mound: Monks Mound, the largest earthen platform mound in North America, rises in multiple terraces to about 30 meters high and forms the core of the ancient civic centre.
  • Central Plaza and mounds: The central plaza and surrounding mound groups that together formed the urban core of the Mississippian city, with evidence of public plazas, residential mounds and craft areas.
  • Woodhenge: A timber circle known as Woodhenge, reconstructed on site, which served an astronomical and ceremonial function in the Mississippian period.
Cahokia
Cahokia Mounds State Historic Site - Visitor Center, 30 Ramey St, Collinsville, IL 62234, USA
38.6539, -90.0646

How to Get to Cahokia #

Cahokia Mounds State Historic Site is near Collinsville, Illinois, on the Illinois side of the Mississippi River, roughly 10 miles (≈16 km) east of downtown St. Louis, Missouri. By car from St. Louis follow the main eastbound routes across the river and use local roads toward Collinsville/Cahokia Mounds-signs will direct you to the site, which has visitor parking.

Public transit options are limited outside the St. Louis region; if using regional buses or trains to Collinsville, expect a short taxi or rideshare from the town centre to the park entrance.

Tips for Visiting Cahokia #

  • Start at the Cahokia Mounds Interpretive Center right when it opens to watch the orientation film and get maps before exploring the site.
  • Climb Monks Mound early in the day for the best views over the site and to avoid the hottest part of summer afternoons.
  • Save time to visit the reconstructed Woodhenge and the site markers that explain the calendar alignments-these are often overlooked by visitors who concentrate only on the larger mounds.
  • Visit on a weekday morning or late afternoon to avoid weekend school groups and bus tour crowds.

Best Time to Visit Cahokia #

Best visited from spring through early autumn when weather is pleasant for exploring the outdoor archaeological site.

Spring
April-May · 8-20°C
Pleasant temperatures and flowering fields - good for walking the park and interpretive trails.
Summer
June-August · 20-32°C
Warm to hot and humid; this is the busiest time for visitors and outdoor programming.
Autumn
September-October · 5-20°C
Cooler, drier weather and fall foliage; comfortable for exploring the earthworks.

Weather & Climate near Cahokia #

Climate

Cahokia's climate is classified as Hot-Summer Continental - Hot-Summer Continental climate with hot summers (peaking in July) and freezing winters (coldest in January). Temperatures range from -7°C to 32°C. Moderate rainfall (970 mm/year).

Temperature & Rainfall
Temperature Range
32°
Warmest Month
-7°
Coldest Month
Monthly Conditions

January

January is the coldest month with highs of 3°C and lows of -7°C. Moderate rainfall (51 mm).

Comfort

-2°
Feels Like Freezing
-2°C
Temperature
-7°

Weather

51 mm
Rainfall
4.0 m/s
Wind
Light Breeze

February

February is cold with highs of 6°C and lows of -4°C. Moderate rainfall (57 mm).

Comfort

Feels Like Cold
C
Temperature
-4°

Weather

57 mm
Rainfall
3.9 m/s
Wind
Light Breeze

March

March is cold with highs of 13°C and lows of 1°C. Regular rainfall (88 mm).

Comfort

Feels Like Cold
C
Temperature
13°

Weather

88 mm
Rainfall
4.2 m/s
Wind
Light Breeze

April

April is cool with highs of 19°C and lows of 7°C. Regular rainfall (94 mm).

Comfort

13°
Feels Like Cool
13°C
Temperature
19°

Weather

94 mm
Rainfall
4.2 m/s
Wind
Light Breeze

May

May is mild with highs of 24°C and lows of 12°C. The wettest month with heavy rain (102 mm).

Comfort

18°
Feels Like Mild
18°C
Temperature
12° 25°

Weather

102 mm
Rainfall
3.3 m/s
Wind
Light Breeze

June

June is mild with highs of 29°C and lows of 18°C. Regular rainfall (94 mm).

Comfort

23°
Feels Like Mild
23°C
Temperature
18° 29°

Weather

94 mm
Rainfall
2.9 m/s
Wind
Calm

July

July is the warmest month with highs of 32°C and lows of 20°C. Regular rainfall (94 mm).

Comfort

26°
Feels Like Warm
26°C
Temperature
20° 32°

Weather

94 mm
Rainfall
2.5 m/s
Wind
Calm

August

August is warm with highs of 31°C and lows of 19°C. Regular rainfall (82 mm).

Comfort

25°
Feels Like Warm
25°C
Temperature
19° 31°

Weather

82 mm
Rainfall
2.4 m/s
Wind
Calm

September

September is mild with highs of 27°C and lows of 14°C. Regular rainfall (82 mm).

Comfort

21°
Feels Like Mild
21°C
Temperature
14° 27°

Weather

82 mm
Rainfall
2.5 m/s
Wind
Calm

October

October is cool with highs of 21°C and lows of 8°C. Moderate rainfall (69 mm).

Comfort

14°
Feels Like Cool
14°C
Temperature
21°

Weather

69 mm
Rainfall
3.1 m/s
Wind
Light Breeze

November

November is cold with highs of 13°C and lows of 2°C. Regular rainfall (82 mm).

Comfort

Feels Like Cold
C
Temperature
13°

Weather

82 mm
Rainfall
3.7 m/s
Wind
Light Breeze

December

December is cold with highs of 6°C and lows of -4°C. Moderate rainfall (75 mm).

Comfort

Feels Like Cold
C
Temperature
-4°

Weather

75 mm
Rainfall
3.8 m/s
Wind
Light Breeze

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