As of 2008, Iowa has an estimated population of 3,002,555, which is an increase of about 19,000 or 0.6%, from the prior year and an increase of 76,000 or 2.6%, since the year 2000. This is the first time the state has topped the three million mark in population. The U.S. Census Bureau has not released specific demographic information for 2008. In 2007 the state had a natural increase since the last census of 53,706 people (that is 197,163 births minus 143,457 deaths) and a decrease due to net migration of 11,754 people out of the state. Immigration from outside the United States resulted in a net increase of 29,386 people, while migration within the country produced a net loss of 41,140 people. 6.1% of Iowa's population were reported as under the age of five, 22.6% under 18, and 14.7% were 65 or older. Males made up approximately 49.2% of the population. The population density of the state is 52.7 people per square mile. The center of population of Iowa is located in Marshall County, in the city of Marshalltown.
Iowa's population included about 97,000 foreign-born (3.3%). Iowans are mostly of Western European descent. The five largest ancestry groups in Iowa are: German (35.7%), Irish (13.5%), English (9.5%), American (6.6%) and Norwegian (5.7%).
The racial make up of the state is 91.0% White (non-Hispanic), 3.8% Hispanic, 2.5% Black or African American, 1.6% Asian, and 0.4% American Indian. One percent of respondents report two or more races.
Iowa's population is more urban than rural, with 61 percent living in urban areas in 2000, a trend that began in the early 20th century. Iowa, in common with other Midwestern states (especially Kansas, Nebraska, North Dakota, and South Dakota), is feeling the brunt of rural flight, although Iowa has been gaining population since approximately 1990. Eighty-nine percent of the total number of cities in those states have fewer than 3,000 people; hundreds more have fewer than 1,000. Between 1996 and 2004, almost one-half million people, nearly one-half with college degrees, left the five states, and headed for major population centers like Minneapolis, Kansas City, and Chicago. The shift from rural to urban has caused population increases in more urbanized counties such as Dallas, Johnson, Linn, and Polk, at the expense of more rural counties. Some communities, such as Denison and Storm Lake, have mitigated this population loss through gains in immigrant laborers.
A 2001 survey from the City University of New York found that 52% of Iowans are Protestant, while 23% are Roman Catholic, and other religions made up 6%. 13% responded with non-religious, and 5% did not answer. The largest Protestant denominations by number of adherents are the Evangelical Lutheran Church in America with 268,543; and the United Methodist Church with 248,211.
The study Religious Congregations & Membership: 2000 found that in the southernmost two tiers of Iowa counties and in other counties in the center of the state, the largest religious group was the United Methodist Church; in the northeast part of the state, including Dubuque and Linn counties (where Cedar Rapids is located), the Roman Catholic Church was the largest; and in ten counties, including three in the northern tier, the Evangelical Lutheran Church in America was the largest. The study also found rapid growth in Evangelical Christian denominations.
Historically, religious sects and orders who desired to live apart from the rest of society established themselves in Iowa, such as the Amish and Mennonite near Kalona and in other parts of eastern Iowa such as Davis County and Buchanan County. Other religious sects and orders living apart include Quakers around West Branch and Le Grand, German Pietists who founded the Amana Colonies, followers of Transcendental Meditation who founded Maharishi Vedic City, and Cistercian monks and nuns at the New Melleray and Our Lady of the Mississippi Abbies near Dubuque.
William Labov and colleagues, in the monumental Atlas of North American English found that the English spoken in Iowa divides into two large linguistic regions. Natives of northern Iowa — including Sioux City, Fort Dodge, and the Waterloo region — tend to speak the dialect that linguists call North Central American English, which is also found in North and South Dakota, Minnesota, Wisconsin, and Michigan. Natives of central and southern Iowa — including such cities as Council Bluffs, Des Moines, and Iowa City — tend to speak the "North Midlands" dialect also found in Nebraska, central Illinois, and northern Indiana.
Iowa has four primary interstate highways. Interstate 29 goes along the western edge of the state through Council Bluffs and Sioux City. Interstate 35 goes from the southern border to the northern border through the center of the state, including Des Moines. Interstate 80 goes from the west end of the state to the east end through Council Bluffs, Des Moines, Iowa City, and the Quad Cities. Interstate 74 has its western terminus at the junction with Interstate 80 in northeastern Davenport, Iowa. Interstate 380 is an auxiliary Interstate Highway, which runs from Interstate 80 near Iowa City through Cedar Rapids ending in Waterloo and is part of the Avenue of the Saints highway.
Iowa has a number of major United States highways. U.S. Route 18 runs along the northern edge of the state from South Dakota to Wisconsin. U.S. Route 20 runs from Sioux City through Fort Dodge and Waterloo before crossing into Illinois in Dubuque. U.S. Route 30 runs from the Nebraska border just north of Council Bluffs through Cedar Rapids and crossing into Illinois in Clinton, staying north of Interstate 80.
U.S. Route 6 winds its way along a similar path to Interstate 80, from Council Bluffs through the Quad Cities into Illinois. U.S. Route 34 runs along the southern part of the state from Nebraska through Burlington to Illinois. U.S. Route 59 runs a path similar to Interstate 29, from south to north along the western edge of the state. U.S. Route 61 runs from the southeastern edge of Iowa in Keokuk through Burlington, the Quad Cities, and into Illinois in Dubuque. U.S. Route 63 runs south from Missouri north through Waterloo and into Minnesota along the eastern central part of the state. U.S. Route 65 and U.S. Route 69 run from Missouri to Des Moines and into Minnesota on paths similar to Interstate 35.
U.S. Route 71 and U.S. Route 75 run a south to north path along the western edge of the state. U.S. Route 169 is a south to north highway in the west central part of the state. U.S. Route 218 runs almost entirely within the state of Iowa, from the southern edge in Keokuk through Iowa City, Cedar Rapids, and Waterloo on its way to Minnesota.
Iowa is served by a few major airports including the Des Moines International Airport, the Eastern Iowa Airport, Quad City International Airport, which is located in Moline, Illinois, and Eppley Airfield, located in Omaha, Nebraska. Smaller airports in the state include the Dubuque Regional Airport, Fort Dodge Regional Airport, Mason City Municipal Airport, Sioux Gateway Airport, Southeast Iowa Regional Airport, and Waterloo Regional Airport.
Amtrak's California Zephyr serves the south of Iowa with stops at Burlington, Mount Pleasant, Ottumwa, Osceola, and Creston on its daily route between Chicago and Emeryville, California (across the bay from San Francisco). Burlington and Fort Madison are also served by Amtrak's Southwest Chief, running daily between Chicago and Los Angeles.