Arlington County VA was previously known as Alexandria County VA and is named after Henry Bennet, the Earl of Arlington. Arlington County VA was originally part of Fairfax County VA when Virginia was still a colony and before it became a state. Arlington County VA at one point had been ceded to the United States of America under the 1790 Residency Act and became part of the District of Columbia. The retrocession, or return, of the county back to Virginia happened in 1846 after legislation was passed by both Congress and the State of Virginia. Arlington VA did not become the official county until 1920. A movement started to rename County to Arlington VA when the separation of 1870 created the City and County of Alexandria VA, which became confusing since they both had the same name. Arlington County VA is now the 6th largest in Virginia, after the 2018 Census, with a population exceeding 237,000 residents. If Arlington VA ever became a City, it would be considered the 4th largest in the state. Between new home construction and the historic homes that still occupy the area today, an extensive knowledge of plumbing is required to be able to work on all types of plumbing systems that have evolved over the years since the advent of the international plumbing code.