As a result of the November 5, 2019 elections, control of the House of Delegates has flipped from a narrow Republican majority (51-49) in the 2018-2020 session to a likely (2 races are still too close to call) 55-45 Democratic majority in the upcoming session.
The key to the party flip was actually that Democratic candidates kept hold of all of the gains they made in 2017 (despite not running down-ballot from a successful gubernatorial candidate). No district that had a Democratic representative changed to Republican control in 2019. In addition, Democrats were able to pick up at least 5 (possibly up to 7) Republican-held districts. These are all generally suburban/exurban districts, speaking to the expansion of the Democratic party’s constituency in 2019 “purple state” America.
Individually, there were a number of key elections that took place in the House of Delegates this year. 14 district elections did not have an incumbent on the ballot and 26 elections (including some of the open seat races) were deemed “battleground” races by Ballotpedia.