I'm not an historian and would refer you to some sites on my links page where you can get a lot of good information on Caddo Parish history. This is just an overview. For slave research I recommend the book "No Land Only Slaves" Vol 3 for Caddo Parish by Smith and Lehman.

Caddo Parish was created on January 18, 1838, from Natchitoches Parish and the parish was named in honor of the Caddo Native American people. The Parish seat is Shreveport. It is bordered by Miller County, AR (north), Lafayette County, AR (northeast), Bossier Parish (east), Red River Parish (southeast), De Soto Parish (south), Panola County, TX (southwest), Harrison County, TX (west), Marion County, TX (west), Cass County, TX (northwest). Cites, Towns and Communities include Belcher, Blanchard, Gilliam, Greenwood, Hosston, Ida, Mira, Mooringsport, Oil City, Rodessa, Shreveport, and Vivian.

One of the sixty-four parishes of Louisiana, a parish is the same as a county in any other state, as Louisiana is the only state to have parishes. Early on, however, Louisiana was divided into counties. In 1804 President Thomas Jefferson appointed William C. C. Claiborne as governor of the Territory of Orleans, as Louisiana was known in its first years. On April 10, 1805, Louisiana was divided into twelve counties. The largest, Natchitoches County, included all of Louisiana north of Rapides County and west of Washita (Ouachita) County. To better understand the vastness of this area, nine parishes were subsequently formed from this area: Bienville, Bossier, Caddo, Claiborne, DeSoto, Natchitoches, Red River, Sabine, and Webster.

The legislature soon established nineteen parishes to coexist with the counties. In 1812, when Louisiana became a state, North Louisiana included Natchitoches, Ouachita, Warren, Catahoula, Concordia, and Rapides Counties. People were heading north and west into Texas from Louisiana, and enough of a population existed in Natchitoches County to create Claiborne Parish, named for the governor, in 1828. This parish consisted of all the land east of the Red River in northern Natchitoches County.

In 1835 the Caddo Indians ceded their land to the United States, and the area was opened up for settlement. Within three years the area had enough people to create another parish. Thus, Caddo Parish was created on January 18, 1838. The name, suggested by legislation member W. H. Sparke, refers to the Caddo Indians. Caddo’s first parish seat was at the Wallace family home situated along Wallace Lake, but it eventually moved to Shreveport. The boundaries of the new parish were not set until 1841. Originally Caddo Parish was framed by the Arkansas line at the north and the Red River at the east, but it extended farther south than it does today. The western boundary was the line dividing the established United States from the territory which had been part of the Louisiana Purchase. The line was accepted by settlers in the area, but in 1841 a survey of the border was made and determined to be seven miles east of the generally accepted line; therefore, Louisiana lost a stretch of land seven miles wide and about seventy miles long. (This area is now part of Harrison, Marion, Cass, and Bowie Counties in Texas).

In 1843 DeSoto and Sabine Parishes were created and took land from the southern part of Caddo Parish. In 1845 the state created a new constitution which was based solely on the parish system, and the counties evaporated. In 1845 the state of the parish’s western boundary was altered when Texas was annexed to the Union. No longer would the western boundary be an international boundary. But that has not been the only boundary change. The course of the Red River, the eastern boundary, has changed often, although the river as a boundary has not. Several sections of land east of the river, which appear to be in Bossier Parish, actually belong to Caddo Parish, and the opposite is true for Bossier Parish. Settlers bought the land in Northwest Louisiana from the government and established plantations, primarily growing cotton, which was the staple crop of the South. By 1860 Caddo Parish was leading in cotton production in the state with Carroll Parish (which had not yet divided into East and West Carroll Parishes) following closely behind. With the onslaught of the Civil War, military activity accelerated from June until December of 1861 with some of the parishes surpassing their required number of soldiers. The parishes in the river areas of North Louisiana, such as Caddo, Carroll, Bossier, and Ouachita had pulled together several companies, and these parishes subsequently increased their war efforts with more military units, such as the Caddo Rifles in North Louisiana.

In 1873 the state was still suffering greatly from the harshness of the Reconstruction government. Caddo, Bossier, and DeSoto Parishes found the situation intolerable and attempted to break away from Louisiana to join Texas. For this to happen, Louisiana’s legislature would have had to approve, and the carpetbaggers serving as members would not allow it. Sawmills came to the area because of the timber, and steamboats and railroads transported the lumber to the Northeast factories. Cotton and timber served as the greatest economic resources until the turn-of-the-century; however, farmers in Caddo Parish were frustrated. Drilling water wells for their livestock or for drinking water for themselves proved useless, as their water continuously came out sour. Some began to wonder if natural gas could be causing the problem.

In 1901 oil was discovered near Beaumont, Texas at Spindletop and at Jennings and at White Castle, Louisiana. Four years later in May, five barrels of oil were produced in the Caddo-Pine Island Field. By 1911 the Gulf Refining Company had successfully drilled oil on Caddo Lake; this was the first off-shore drilling in the nation. The 1930’s saw another oil boom as people began to flock to Rodessa.

source: http://www.mylouisianagenealogy.com/la-county-caddo.html#eh