It is believed to have been named either for Richard Montgomery, an American Revolutionary War general killed in 1775 while attempting to capture Quebec City, or for the Welsh county of Montgomeryshire, which was named after one of William the Conqueror's main counselors, Roger de Montgomerie, since it was part of the Welsh Tract, an area of Pennsylvania settled by Quakers from Wales.

Many Montco residents work in the city, but the county is also a major employment center with large business parks in Blue Bell, Lansdale, Fort Washington, Horsham, and King of Prussia attracting thousands of workers from all over the region.

These boroughs, townships, and home rule municipalities are located in Montgomery County: Census-designated places are geographical areas designated by the United States Census Bureau for the purposes of compiling demographic data.

In most southern areas of the county and along the Schuylkill River including Pottstown a humid subtropical climate (Cfa) exists.

However, Montgomery County residents have voted for the Democratic presidential nominee since 1992, with the margins progressively increasing between every election, except in 2012.

In the 2016 U.S. Senate and Pennsylvania Attorney General elections, Montgomery County voted for Katie McGinty and Josh Shapiro, both Democrats.

Democrats have also won several elections in the Pennsylvania General Assembly in recent years, including two GOP-leaning State House districts in 2004, the 148th with Mike Gerber and the 153rd with current Governor Josh Shapiro.

As of the November 2019 election: On July 24, 2013, Montgomery County Register of Wills D. Bruce Hanes, a Democrat, announced he would begin issuing marriage licenses to same-sex couples, flouting Pennsylvania law banning such unions.

The Republican administration of Governor Tom Corbett filed suit in the Commonwealth Court of Pennsylvania in an attempt to block Hanes from licensing same-sex marriage.

[28] Commonwealth Court Judge Dan Pellegrini ordered Hanes in September 2013 to stop issuing same-sex marriage licenses.

After Federal Judge John Jones threw out Pennsylvania's ban on same-sex marriage in May 2014, calling it unconstitutional, offices in other counties were able to issue these licenses, while Hanes had to wait for the ruling against him to be removed.