Population

This map shows population growth since 2010 in each census tract. Population is growing fastest in the northern and southern suburbs, but Downtown and the Northeast side are also growing fast.

EXPLORE MAP

Population Growth

Population 1830-2010

Line chart showing population growth of both Indianapolis and Marion County.
Source: U.S. Census Get the data

Indianapolis grew exponentially until the 1930s. The Great Depression and World War II slowed growth. Suburbanization caused most growth to take place outside the city limits, so Marion County’s population grew more quickly than Indianapolis.

In 1970, Unigov combined city and county governments and expanded the city limits to include most of Marion County. A population decline in the 1970s has been followed by steady growth in the decades since. Marion County has a larger population than Indianapolis because several cities are excluded from Unigov, including Beech Grove, Speedway, and Lawrence.

The estimated population of Marion County now approaches one million residents, fueled by growth downtown, in Decatur and Franklin Townships, and on the Northeast Side.

Marion County Population Since 2010

Line graph showing that Marion County's population increase by nearly 100,000 people from 2010 to 2023.

Population growth is driven by births, not migration

In the 2000s net migration was negative. People moving away outnumbered people moving to the city. This slowed the growth of the city. Since 2011 net migration has increased. This is due to increase international migration. Net domestic migration is still negative. Much of this domestic outmigration is caused by residents moving to suburban counties. Marion County’s population growth has come mostly from natural increase as births outnumber deaths about 2-to-1.

Components of change, 2001-2019

The chart shows the differences between natural increase in population versus net migration. The 2000s net migration was negative, however, since 2011 net migration has increased.
Source: Indiana Business Research Center View chart and get data

Suburbanization

Center Township, once home to most Marion County residents, is now only a fraction of the county population.

Proportion of Marion County population by township.

The bar chart shows the breakdown of Marion County population based on township. In all years shown, between 1850 and 2019, Center Township has a greater population than all other townships in the county.
U.S. Census (Decennial census except American Community Survey 1-Year Average in 2019) Get the data

In the early decades of suburbanization, households moved from the center city to outer areas within Marion County. These shifts are evident in the population of Marion County townships.

In 1950, 64% of Marion County residents lived in Center Township. After population loss in Center Township and new development in outlying townships, less than one-in-five Marion County residents lived in Center Township in 2019.

Animated image showing the movement and growth within Marion County's population from 1970 to 2018.

Suburbanization led to the rapid growth of outlying counties since 1970.

Each dot = 100 residents

Since the middle of the 20th century, population has grown quickly in places outside Indianapolis’ original city limits.

In 1970, most population is still located within the Indianapolis city limits. Outlying towns like Noblesville, Brownsburg, and Avon are visible as distinct population centers.

In the ensuing decades, these towns are absorbed into the larger metropolitan population as rapid growth expands north, west, and south.

Demographics

The line graph shows the white population versus the population of color in Indianapolis. The white population is greater than the population of color for all years represented (1900 to 2020). The gap between the two populations is the least by 2020.
Source: U.S. Census Get the data

White population peaked in 1970 and has fallen since. As the population of color rose, these two demographic groups are nearly equal in number. People of color includes anyone who chooses a race other than white or choose and ethnicity of Hispanic or Latino in the census.

Growth rate by race and ethnicity

Graph showing the change in population from 2010 to 2023, broken down by race. The Asian and Hispanic populations have grown the most.

Population by race and ethnicity

Graph showing the 2023 population, broken down by race. The Asian, Hispanic, and Black demographic combined make up about fifty percent of the population, while the white demographic makes up the other fifty percent.

International migration and higher birth rates among people of color have led to growth among Asian, Black, and Latino residents, while there are fewer White residents compared to 2010. The Asian population has grown very fast since 2010.

Population of Marion County by age and gender

1850

Two bar charts comparing population of Marion County in 1850 by age and gender. The 15 to 29 year age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups.

This is called an “expansive” age pyramid. There are many youth and few older adults. It reflects the pioneer nature of early Indianapolis: high fertility rates, low life-expectancy, and many working age adults. Men outnumber women in the prime working years, another indication of Indianapolis’ pioneer quality.

1900

Two bar charts comparing population of Marion County in 1900 by age and gender. The 15 to 24 and the 25 to 34 year age groups make up the largest portion. There is a near 50/50 split between males and females in all age groups.

By 1900, the age pyramid is similar to the United States overall. Longer life expectancy led to more older adults, and fertility rates declined. Men no longer outnumbered women at the prime working ages.

1970

Two bar charts comparing population of Marion County in 1970 by age and gender. The 5 to 14 year age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups.

The bulge in the bottom of this chart, ages 0-14, represents the baby boom generation, when, as World War II ended, fertility rates were very high. People were living longer, and one sixth of individuals are age 55 or older.

1990

Two bar charts comparing population of Marion County in 1990 by age and gender. The 25 to 34 year age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups except for the 65 and up age group which has more females than males.

Twenty years later, baby boomers were represented in the 25 to 34 year old category, though their proportion shrank as many left Marion County for the suburbs. Marion County’s older adult population continued to grow.

2019

Two bar charts comparing population of Marion County in 2019 by age and gender. The 25 to 34 year age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups except for the 65 and up age group which has more females than males.

As baby boomers aged and Generation Z was born, the age pyramid flattened into what is called a “stationary” age distribution. This indicates slow growth. It also means there are more dependent people (those too old or too young to work) who are supported by the income of working age adults.

2019 Marion County age distribution by race

Age pyramids vary for each race. For White individuals, the age pyramid is inverted, indicating an aging and shrinking population. Black and Latino age distribution are truly “pyramid” shaped, indicating growing populations. There are relatively few older Latino and Asian individuals. Many of these residents are foreign born, and these populations will age as recent immigrants grow older.

White (Non-Hispanic/Latino)

Two bar charts comparing white, non-hispanic population of Marion County in 2019 by age and gender. The 24 to 34 and 65 and up age groups make up the largest portion. There is a near 50/50 split between males and females in all age groups except for the 65 and up group which has more females.
Source: U.S. Census – American Community Survey 1-Year Average Get the data

Black

Two bar charts comparing Black population of Marion County in 2019 by age and gender. The 5 to 14 and 15 to 24 age groups make up the largest portion. Nearly all age groups have more females than males except for the less than 5 and 5 to 14 age groups.
Source: U.S. Census – American Community Survey 1-Year Average Get the data

Hispanic/Latino

Two bar charts comparing hispanic/latino population of Marion County in 2019 by age and gender. The5 to 14 age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups.
Source: U.S. Census – American Community Survey 1-Year Average Get the data

Asian

Two bar charts comparing asian population of Marion County in 2019 by age and gender. The 25 to 34 age group makes up the largest portion. There is a near 50/50 split between males and females in all age groups except for the less than 5, 45 to 54, and 65 and up groups which have more females.
Source: U.S. Census – American Community Survey 1-Year Average Get the data

Atlas Sources

Demographic information is from the U.S. Census and the American Community Survey. Components of growth, such as births, deaths, and migration, are from Indiana Business Research Center.

Additional Information

Read these Encyclopedia of Indianapolis Entries for more information.

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