Explanation: The provided data indicates that in 2020, the St. Louis Metropolitan Statistical Area (MSA) had a population of 2,820,253, ranking it as the 21st largest in the United States, not exceeding 3 million and not ranked 23rd.

Explanation: The core city of the Greater St. Louis metropolitan area is St. Louis, Missouri. However, it is situated on the west bank of the Mississippi River, not the east bank.

Explanation: The Greater St. Louis metropolitan area primarily encompasses parts of two U.S. states: Missouri and Illinois. Iowa is not included in this designation.

Explanation: The total area of Greater St. Louis is documented as 8,458 square miles, which is equivalent to 21,910 square kilometers. The question specifies square kilometers, and the value provided aligns with the total area.

Explanation: According to the 2020 census data, the St. Louis Metropolitan Statistical Area (MSA) recorded a population of 2,820,253, positioning it as the 21st largest MSA nationally.

Explanation: Data from 2020 confirms that the St. Louis Combined Statistical Area (CSA) held the 20th position among the largest CSAs in the United States, with a population totaling 2,909,003.

Explanation: The St. Louis MSA experienced a decline in its national ranking, falling below the top 20 largest MSAs in 2017, which was noted as the first occurrence since 1940.

Explanation: Greater St. Louis is situated within the Central Time Zone (CT), not the Mountain Time Zone (MT).

Explanation: The area codes serving the Greater St. Louis region indeed include 314, 618, and 573, among others such as 217, 235, 447, 557, 636, and 730.

Explanation: The Illinois counties that are officially part of the St. Louis Metropolitan Statistical Area (MSA) are indeed collectively referred to as the 'Metro East'.

Explanation: While there are two municipalities named Troy in the Greater St. Louis area, the one in Missouri is located in Lincoln County, not St. Charles County. The other Troy is in Illinois's Madison County.

Explanation: St. Louis, Missouri, serves as the principal core city for the Greater St. Louis metropolitan area.

Explanation: The Greater St. Louis metropolitan area is comprised of counties and cities located in both Missouri and Illinois.

Explanation: In the year 2020, the St. Louis Metropolitan Statistical Area (MSA) was ranked as the 21st largest in the United States.

Explanation: The St. Louis MSA dropped out of the nation's top 20 largest MSAs in 2017, marking the first time this had occurred since 1840.

Explanation: Greater St. Louis observes the Central Time Zone (CT).

Explanation: The Illinois counties officially designated as part of the St. Louis MSA are Bond, Calhoun, Clinton, Jersey, Macoupin, Madison, Monroe, and St. Clair, collectively known as the 'Metro East'.

Explanation: Boone County, Missouri, is not listed as part of the St. Louis MSA. The Missouri counties included are Crawford (specifically Sullivan), Franklin, Jefferson, Lincoln, St. Charles, St. Louis County, and Warren.

Explanation: Historically, the region now known as Greater St. Louis was primarily inhabited by the Illini Confederacy, not the Iroquois Confederacy.

Explanation: St. Louis earned the historical nickname 'Mound City' due to the significant presence of indigenous earthwork mounds in the area, particularly those associated with the Cahokia Mounds complex.

Explanation: Pierre Laclede Liguest and Auguste Chouteau founded St. Louis in 1764 as a French fur trading post. However, the strategic location was near the confluence of the Mississippi and Missouri Rivers, not the Ohio River.

Explanation: Following its French founding, St. Louis was transferred to Spanish control in 1770. It later became part of the United States through the Louisiana Purchase in 1803, not through British control.

Explanation: While the Louisiana Purchase incorporated St. Louis into the United States and facilitated its growth, its primary significance was as a starting point for westward exploration (Lewis and Clark Expedition) and as a hub for trade along the Mississippi River, not specifically as a major port for trade with Mexico.

Explanation: The significant population growth in St. Louis between 1840 and 1860 was primarily driven by a large influx of immigrants, particularly from Germany and Ireland, rather than solely industrial development and railroads.

Explanation: Historical records confirm that by the 1890s, St. Louis had achieved the status of the fourth-largest city in the United States in terms of population.

Explanation: In 1904, St. Louis hosted both the Olympic Games and the Louisiana Purchase Exposition (a major international world's fair).

Explanation: The period between World War I and World War II saw the Great Migration, during which a significant number of African Americans relocated to urban centers like St. Louis, substantially increasing its African American population.

Explanation: Construction on the Gateway Arch and Busch Stadium began in the mid-1960s, not the early 1950s, as part of downtown revitalization initiatives.

Explanation: The region now known as Greater St. Louis was historically inhabited by the Illini Confederacy.

Explanation: The nickname 'Mound City' was given to St. Louis due to the historical presence of numerous indigenous earthwork mounds in and around the area, notably the significant Cahokia Mounds.

Explanation: St. Louis was founded in 1764 by Pierre Laclede Liguest and Auguste Chouteau, who established it as a French fur trading post.

Explanation: In 1770, St. Louis was transferred from French to Spanish control as part of territorial adjustments.

Explanation: The Louisiana Purchase in 1803 incorporated St. Louis into the United States and established it as the pivotal starting point for the historic Lewis and Clark Expedition.

Explanation: The period between 1840 and 1860 saw a substantial population surge in St. Louis, largely driven by immigration, with significant numbers arriving from Germany and Ireland.

Explanation: By the 1890s, St. Louis had grown to become the fourth-largest city in the United States.

Explanation: In 1904, St. Louis was the host city for both the Olympic Games and the Louisiana Purchase Exposition, a significant world's fair.

Explanation: The Great Migration, a period of significant African American relocation from the rural South to urban centers, led to a substantial increase in St. Louis's African American population between the World Wars.

Explanation: In 2022, the Gross Metropolitan Product (GMP) for the St. Louis, MO-IL MSA was reported to be $209.9 billion, which is approximately $210 billion.

Explanation: The Gross Metropolitan Product (GMP) for the St. Louis MSA in 2022 was reported as $209.9 billion.

Explanation: In Greater St. Louis, the wholesaling industry generated the highest business revenue, amounting to approximately $71 billion, closely followed by manufacturing at $67 billion.

Explanation: Centene Corporation is a Fortune 500 company headquartered in Greater St. Louis, as of 2021.

Explanation: The East-West Gateway Council of Governments functions as the federally designated metropolitan planning organization (MPO) responsible for regional transportation planning.

Explanation: St. Louis Lambert International Airport is one of the two primary commercial airports serving the Greater St. Louis region.

Explanation: The Greater St. Louis area is served by a total of 132 public school districts.

Explanation: St. Louis's population did peak in 1950. However, the subsequent decline was primarily attributed to residents moving to suburbs that could not be annexed, as the city had reached its boundary limits for expansion, not due to the expansion of city boundaries.

Explanation: According to the 2020 census, St. Louis County, Missouri, reported a population of 1,004,125, significantly exceeding 300,000. The City of St. Louis had a population of 301,578.

Explanation: In the 2020 census, Madison County, Illinois, recorded the highest population among the Illinois counties within the St. Louis MSA, with 264,461 residents.

Explanation: In 2010, approximately 18% of Greater St. Louis's population identified as African American. The figure of 76.9% identified as white.

Explanation: A 2014 Pew Research study indicated that 75% of residents within the St. Louis metro area identified with Christianity.

Explanation: The 2010 United States Census reported the median age for the population residing in Greater St. Louis to be 38.2 years.

Explanation: In 2010, the gender distribution in Greater St. Louis was 47.4% males and 52.6% females, indicating a higher percentage of females.

Explanation: The median income for a household within the St. Louis metropolitan area was reported as $50,900 in the year 2010.

Explanation: Following its population peak in 1950, St. Louis experienced a decline primarily because the city reached its annexation boundaries, prompting residents to move to surrounding, unannexable suburbs.

Explanation: The 2020 census data shows that St. Louis County, Missouri, had a population of 1,004,125, while the City of St. Louis had a population of 301,578, making the county significantly larger.

Explanation: According to the 2010 census data, 76.9% of the population residing in Greater St. Louis identified themselves as white.

Explanation: A 2014 Pew Research study found that 21.0% of residents in the St. Louis metro area identified as having no religious affiliation.

Explanation: The 2010 United States Census indicated that the median age for the population in Greater St. Louis was 38.2 years.

Explanation: Gateway Arch National Park holds the distinction of being the sole National Park situated within the state of Missouri.

Explanation: St. Louis City SC is the professional soccer team representing the Greater St. Louis area in Major League Soccer (MLS).

Explanation: The St. Louis Cardinals, a Major League Baseball team, play their home games at Busch Stadium.