Platte County, Missouri was formed in 1838. Named for the Platte River, the principal river of the county. It rises in Nodaway County, flows south, and empties into the Missouri River. The Lewis and Clark Journal has this entry: "...passed the mouth of a small river ten miles above the Kansas called by the French Petite River Platte (or Shoal River), from the number of falls in it." The French compared it to the larger Platte River of Nebraska. Locally it was not known as the Little Platte. The name Platte for both rivers has the sense indicated by Lewis and Clark of "shoal" or shallow, which is eminently characteristic of either stream.
At the time of its organization, it had its present boundaries: Buchanan County on the north, Clinton and Clay Counties on the east. The Missouri River separates it on the south and west from the state of Kansas.
On November 16,1839 at a meeting at Martinsville, it was decided by a board of commissioners that the Falls of Platte (later Platte City) be the seat of justice in Platte County. The Platte County Court approved this site as the location of the County Seat on December 4, 1839, due to its central location and officially named the site Platte City. Thus, in the spring of 1840, the town of Martinsville moved over into what is now known as Platte City.
The first circuit court was held at the log cabin of M.D. Faylor in the Falls of Platte on March 25,1839. Construction on the first county courthouse was started in September 1840. It was completed and opened for use in December 1842. The original courthouse was located one block west of where the current courthouse resides. It stood about where Wellsbrook Antiques, the Landmark and Farley Law Office are located. It was a two-story building costing $15,000 to build. Church services of all denominations were held on the second floor. Chairs were by subscription and helped pay the cost of the building. The first church to erect it's own building was the Methodist in 1848, followed by the Baptist in 1850, the Christian, in 1855 and the Catholic, in 1870. The Presbyterian had organized in 1843 and shared the Methodist Church building for services.
Platte City was incorporated as a city in September 1843. A charter was obtained from the Legislature in 1845 for Platte City. At this time Main Street was graded and sidewalks laid.
Source: Platte City Area Chamber of Commerce
Buckley B Anderson and his family moved to Platte County, Missouri about 1847. Buckley and family had left Nauvoo, Illinois in 1846 as part of the Mormon Exodus traveling to Winter Quarters (later known as Florence, near Omaha, Nebraska), before returning to Missouri, settling in to Platte City, Platte County. By 1850, Buckley and family were living in Gallatin Township, Clay County, Missouri.