US firms Edwards Wildman Palmer and Locke Lord have voted in favour of a merger, creating a law firm with revenue of around $675m (£428.7m).

The combination, which will operate as Locke Lord Edwards, is set to go live on 10 January 2015. It will staff around 1,000 lawyers based in 23 offices. Management at both firms had previously signed a letter of intent to merge in September.

Locke Lord chair Jerry Clements will lead the merged entity as its chair, while Edwards Wildman managing partner Alan Levin will become vice chair of the business alongside Locke Lord Chicago litigation partner Dan Schlessinger and Houston energy group co-chair Bill Swanstrom.

The quartet will sit on the combined firm's 15-strong executive committee, which is rounded off by six more partners from Locke Lord, including London corporate finance partner Graham Spitz, and five more from Edwards Wildman.

Despite several departures from Edwards Wildman's City base, the firm has said that London "will continue to be an important focus of the combined firm and one with anticipated growth as a gateway to international business".

In October it emerged that Edwards Wildman Palmer was left with no management figures in London, with office managing partner Nick Bolter thought to have been relieved of his leadership position.

There has been a series of partner departures from the firm's City base in the past few months, including IP partner Ben Goodger, who left for Osborne Clarke, corporate partner Stuart Blythe, who moved to CMS Cameron McKenna and corporate partner Niall McAlister, who joined Olswang.

The combined firm will have offices in Atlanta, Austin, Boston, Chicago, Dallas, Hartford, Hong Kong, Houston, Istanbul, London, Los Angeles, Miami, Morristown, New Orleans, New York, Orange County, Providence, Sacramento, San Francisco, Stamford, Tokyo, Washington DC and West Palm Beach.

Clements said: "This combination will enhance our position in the top tier of US law firms and significantly strengthen our position and product offerings in the middle market. "It will allow us to brand that identity in the global marketplace with a major presence in the Northeast and a stronger footprint in the Midwest, West Coast and southeast regions of the United States, as well as in Asia."

Locke Lord Edwards executive committee members in full (firm):

Jerry Clements (Locke Lord; Austin and Dallas)
Alan Levin (Edwards Wildman; Hartford and New York)
Dan Schlessinger (Locke Lord; Chicago)
Bill Swanstrom (Locke Lord; Houston)
Nick Giovanni (Locke Lord; Chicago)
Michael Gaertner (Locke Lord; Chicago)
Janis Loegering (Locke Lord; Dallas)
Graham Spitz (Locke Lord; London)
David Taylor (Locke Lord; Houston)
Tom Yoxell (Locke Lord; Dallas)
Jeffrey Hsi (Edwards Wildman; Boston and West Palm Beach)
Walter St Onge (Edwards Wildman; Boston)
Heather Stone (Edwards Wildman; Boston)
George Ticknor (Edwards Wildman; Boston)
Jonathan Young (Edwards Wildman; Chicago)