Louisville is located at (38.228870, -85.749534). According to the United States Census BureauU.S. Census Bureau, Louisville Metro (in 2000 measurements for Jefferson County) has a total area of 1,032 km sq (399 mi sq). 997 km sq (385 mi sq) of it is land and 35 km sq (13 mi sq) of it (3.38%) is water. Although the soils and underlying rocks officially put Louisville in the Bluegrass region, the city's landscape is better described as being in a very wide part of the Ohio River flood plain. Louisville's part of the valley is located between two plateaus, the karst topographykarst plateau of Southern Indiana and the Bluegrass plateau of Kentucky, both with an elevation of around 900 feet. Elevations drop off the Indiana plateau very sharply via the Muldraugh Escarpment, whereas the rise in elevation up to the Bluegrass plateau is done more gradually. The flood plain is much longer north to south than it is east to west. For example, within several miles of downtown, the Highlands sitting at 540 feet is out of the thousand year flood plain, whereas areas 10 miles from downtown such as Fairdale and Okolona (both between seven and 11 miles from the river) have the same elevation as downtown Louisville. Most areas in the east end have an elevation from 600 to 700 feet, which with the typically east bound winds, traps in heat and pollutants in. Areas along and west of the south fork of Beargrass Creek (and more generally, Interstate 65I-65) are located where the Ohio River once ran, so the land here is very flat and is composed of harder rocks. Prior to urbanization much of this area was composed of wetlands — early roads through it were laid over wooden planks. This history is occasionally still readilly evident in street names, for example the spoke road Poplar Level, whose name describes its original construction on planks of poplar. 3rd Street was formerly called Central Plank Road for the same reason. As industry, namely Standiford Field airport, moved into the area in the 1950s most creeks through the area were rerouted into ditches to alleviate the area's poor drainage and constant flooding. Areas east of I-65 were generally not in the flood plain and thus are mostly gentle rollings hills composed of soft loess soils, hence the reason roads here (such as Eastern Parkway) are very prone to potholes. The southern quarter of Jefferson County is in the scenic and rugged Knobs region. This is the only part of Jefferson County to not have experienced any urbanization and is today almost entirely parkland for the Jefferson Memorial Forest. The eastern third is in the Eden Shale Hills section of the Bluegrass region and has also experienced less urbanization than the flood plain, although that is starting to change. The Louisville-Jefferson County, KY-IN Metropolitan Statistical Area (MSA), the List of United States metropolitan statistical areas by population43rd largest in the United States, includes the Kentucky counties of Jefferson County, KentuckyJefferson (contiguous with ''Louisville Metro''), Bullitt County, KentuckyBullitt, Henry County, KentuckyHenry, Meade County, KentuckyMeade, Nelson County, KentuckyNelson, Oldham County, KentuckyOldham, Shelby County, KentuckyShelby, Spencer County, KentuckySpencer and Trimble County, KentuckyTrimble. The southern Indiana counties Clark County, IndianaClark, Floyd County, IndianaFloyd, Harrison County, IndianaHarrison and Washington County, IndianaWashington are also included in the Louisville United States metropolitan areaMSA. This MSA is included in the Louisville-Elizabethtown-Scottsburg, KY-IN Combined Statistical Area (CSA), which also includes the Elizabethtown, KentuckyElizabethtown, KY MSA (composed of Hardin County, KentuckyHardin and Larue County, KentuckyLarue Counties) as well as the Scottsburg, IndianaScottsburg, IN Micropolitan Statistical Area. The Louisville CSA ranks 31st in the USA in population. 17% of the state's population lives in Jefferson County and 25% live in counties in the Louisville CSA, and also Jefferson County has 2.5 times more people than Kentucky's second most populous county, Fayette County. 12 of the 15 buildings in Kentucky over 300 feet are located in Downtown Louisville. Almost 40% of the population growth in Kentucky are in Louisville's CSA counties. Source: http://en.wikipedia.org/wiki/Geography_of_Louisville%2C_Kentucky