Butler County was formed by an act of the Assembly of Pennsylvania on March 12, 1800, by severing a portion of land from Allegheny County.

When the county was founded, it had a population of 3,916.

The county had four townships at the time: Connoquenessing, Buffalo, Middlesex and Slippery Rock. It now has 33 townships.

Gen. Richard Butler was the county’s namesake, although he probably never actually visited what is now Butler County.

Butler, who reportedly was born April 1, 1743, in Carlisle, Cumberland County, fought in the Revolutionary War and was killed in action in 1791 by Native Americans in Ohio. Some historical publications say Butler was born in Northern Ireland and his parents later immigrated to Pennsylvania.

Butler is immortalized in a statue placed high on a pedestal at Diamond Park, which is across Main Street from the courthouse.

By another act of the Assembly on April 2, 1803, the county was organized for judicial purposes.

As part of the original founding in 1800, the seat of justice was to be not more than four miles from the center of the county.

So in 1803, the formation of 502,400 acres that comprise Butler County were completed. Of this land, 300 acres were laid out for the borough of Butler, the county seat. Butler was eventually designated a city, which it remains today.

In March 1803, the Legislature passed another act that appointed John McBride, William Elliot and John David as trustees for the county and gave them the power to lay out the county seat.

Butler County’s first commissioners were Matthew White, James Bovard and Jacob Mechling. They became commissioners in 1803.

By 1820, the county’s population had grown to 10,193.

The borough of Butler had at least six taverns, a blacksmith shop, quarries, a gristmill, the Butler Academy, a Presbyterian church and a courthouse, which opened in 1807, according to “Concise History of Butler County Pennsylvania 1800-1950,” written by J. Campbell Brandon in 1962.

The county’s first courthouse was built in 1803. The second was built in 1853, remodeled in 1877 and destroyed by fire in 1883. The current courthouse was built in 1885-86 and was improved in 1907. The stone High Victorian Gothic building was registered in 1977 with the National Register of Historic Places.

In 1991, the County Government Center was built at the intersection of West Diamond and South Jackson streets. The new building and courthouse are connected by a skywalk.