As of July 1, 2006, Kentucky has an estimated population of 4,206,074, which is an increase of 33,466, or 0.8%, from the prior year and an increase of 164,586, or 4.1%, since the year 2000. This includes a natural increase since the last census of 77,156 people (that is 287,222 births minus 210,066 deaths) and an increase due to net migration of 59,604 people into the state. Immigration from outside the United States resulted in a net increase of 27,435 people, and migration within the country produced a net increase of 32,169 people. As of 2004, Kentucky's population included about 95,000 foreign-born (2.3%). The population density of the state is 101.7 people per square mile.
Kentucky's total population has grown during every decade since records began. However, during most decades of the 20th century there was also net out-migration from Kentucky. Since 1900, rural Kentucky counties have experienced a net loss of over 1 million people from migration, while urban areas have experienced a slight net gain.
The center of population of Kentucky is located in Washington County, in the city of Willisburg.
The five largest ancestries in the commonwealth are: American (20.9%), German (12.7%), Irish (10.5%), English (9.7%), African American (7.8%). Only eight Kentucky counties list an ancestry other than "American" as the county's largest, those being Christian and Fulton, where African American is the largest reported ancestry, and the state's most urban counties of Jefferson, Oldham, Fayette, Boone, Kenton, and Campbell, where German is the largest reported ancestry. Southeastern Kentucky was populated by a large group of Native Americans of mixed heritage, also known as Melungeons, in the early 19th century. Groups like the Ridgetop Shawnee are organizing the descendants of those early Native American settlers.
African Americans, who made up one-fourth of Kentucky's population prior to the Civil War, declined in number as many moved to the industrial North in the Great Migration. Today 44.2% of Kentucky's African American population is in Jefferson County and 52% are in the Louisville Metro Area. Other areas with high concentrations, besides Christian and Fulton Counties, are the city of Paducah, the Bluegrass, and the city of Lexington. Many mining communities in far Southeastern Kentucky also have populations between five and 10 percent African American.
In 2000, The Association of Religion Data Archives reported that of Kentucky's 4,041,769 residents:
Today Kentucky is home to several seminaries. Southern Baptist Theological Seminary in Louisville is the principal seminary for the Southern Baptist Convention. Louisville is also the home of the Louisville Presbyterian Theological Seminary. Lexington has two seminaries, Lexington Theological Seminary, and the Baptist Seminary of Kentucky. Asbury Theological Seminary is located in nearby Wilmore. In addition to seminaries, there are several colleges affiliated with denominations. Transylvania in Lexington is affiliated with the Disciples of Christ. In Louisville, Bellarmine and Spalding are affiliated with the Roman Catholic Church. In Owensboro, Kentucky, Kentucky Wesleyan College is associated with the Methodist Church and Brescia University is associated with the Roman Catholic Church. Louisville is also home to the headquarters of the Presbyterian Church (USA) and their printing press. Louisville is also home to a sizable Muslim and Jewish population.
Religious movements were important in the early history of Kentucky. Perhaps the most famous event was the interdenominational revival in August 1801 at the Cane Ridge Meeting house in Bourbon County. As part of what is now known as the "Western Revival", thousands began meeting around a Presbyterian communion service on August 6, 1801, and ended six days later on August 12, 1801 when both humans and horses ran out of food. Some claim that the Cane Ridge revival was propagated from an earlier camp meeting at Red River Meeting House in Logan County.
Kentucky is served by five major interstate highways (I-75, I-71, I-64, I-65, I-24), nine parkways, and three bypasses and spurs. The parkways were originally toll roads, but on November 22, 2006, Governor Ernie Fletcher ended the toll charges on the William H. Natcher Parkway and the Audubon Parkway, the last two parkways in Kentucky to charge tolls for access. The related toll booths have been demolished.
Ending the tolls some seven months ahead of schedule was generally agreed to have been a positive economic development for transportation in Kentucky. In June 2007, a law went into effect raising the speed limit on rural portions of Kentucky Interstates from 65 to 70 miles per hour.
Greyhound provides bus service to most major towns in the state.
Amtrak, the national passenger rail system, provides service to Ashland, South Portsmouth and [[Fulton, Kenthe rails of kentucky are very populuartucky]]. The Cardinal, Trains 50 and 51, is the line that offers Amtrak service to Ashland and South Portsmouth. Amtrak Trains 58 and 59, the City of New Orleans, serve Fulton. The Northern Kentucky area, is served by the Cardinal at the Cincinnati Museum Center at Union Terminal. The Museum Center is just across the Ohio River in Cincinnati.
As of 2004, there were approximately 2,640 miles (4,250.4 km) of railways in Kentucky, with about 65% of those being operated by CSX Transportation. Coal was by far the most common cargo, accounting for 76% of cargo loaded and 61% of cargo delivered.
Bardstown features a tourist attraction known as My Old Kentucky Dinner Train. Run along a 20-mile (30 km) stretch of rail purchased from CSX in 1987, guests are served a four-course meal as they make a two-and-a-half hour round-trip between Bardstown and Limestone Springs. The Kentucky Railway Museum is located in nearby New Haven.
Other areas in Kentucky are reclaiming old railways in rail trail projects. One such project is Louisville's Big Four Bridge. If completed, the Big Four Bridge rail trail will contain the second longest pedestrian-only bridge in the world. The longest pedestrian-only bridge is also found in Kentucky — the Newport Southbank Bridge, popularly known as the "Purple People Bridge", connecting Newport to Cincinnati, Ohio.
Kentucky's primary airports include Louisville International Airport (Standiford Field), Cincinnati/Northern Kentucky International Airport (CVG), and Blue Grass Airport in Lexington. Louisville International Airport is home to UPS's Worldport, its international air-sorting hub. There are also a number of regional airports scattered across the state.
On August 27, 2006, Kentucky's Blue Grass Airport in Lexington was the site of a crash that killed 47 passengers and 2 crew members aboard a Bombardier Canadair Regional Jet designated Comair Flight 191, or Delta Air Lines Flight 5191, sometimes mistakenly identified by the press as Comair Flight 5191. The lone survivor was the flight's first officer, James Polehinke, who doctors determined to be brain damaged and unable to recall the crash at all.
Being bounded by the two largest rivers in North America, water transportation has historically played a major role in Kentucky's economy. Most barge traffic on Kentucky waterways consists of coal that is shipped from both the Eastern and Western Coalfields, about half of which is used locally to power many power plants located directly off the Ohio River, with the rest being exported to other countries, most notably Japan.
Many of the largest ports in the United States are located in or adjacent to Kentucky, including:
As a state, Kentucky ranks 10th overall in port tonnage.
The only natural obstacle along the entire length of the Ohio River was the Falls of the Ohio, located just west of Downtown Louisville.