(Reuters) - International mega-firm Dentons is squeezing yet another U.S. combination into 2020, announcing plans to join forces with an 80-lawyer firm.

As part of its strategy to scale up across the United States, Dentons said Tuesday it will combine with Iowa-based Davis Brown, which has three offices in the state and has "dominated that marketplace for so many years," said Dentons global chairman Joe Andrew.

"It's about Davis Brown, the talent. But secondly, Iowa is one of the fastest-growing financial services-company hubs and insurance-company hubs in the country," Andrew said, adding that there are about 80 financial services and insurance companies based in Des Moines.

Davis Brown has offices in Ames, Des Moines and West Des Moines. The firm offers a wide variety of legal services, including agribusiness, construction, intellectual property, litigation, mergers and acquisition, real estate, tax, and wills, trusts and estates.

Combining with Dentons allows Davis Brown to tap into its global platform while maintaining local control of its rates and attorneys, said John Pietila, president of Davis Brown. About 10,000 attorneys in 77 countries are part of Dentons' network.

Pietila said his firm was looking to grow in the wake of several major Midwestern-based law firm mergers since last year, but it didn't want to sacrifice its independence or culture.

"Give us the scale and let us run with what we see as the right vision for a law firm in this market," Pietila said.

Davis Brown will be the fourth law firm to sign onto Dentons' so-called "Golden Spike" strategy, which the firm announced last fall. The name is borrowed from the railroad spike that tied together the Central Pacific Railroad and the Union Pacific Railroad a century and a half ago, creating the First Transcontinental Railroad.

Dentons has said its goal is to become the first truly national U.S. law firm, with a presence in midmarket commercial and financial hubs along with the largest markets.

Andrew said there's more outside corporate legal spending in Des Moines than there is in the entire country of India. "People do not understand the size of these markets," he said.

Tuesday's announcement comes three weeks after Dentons wrapped up its combination with another Golden Spike partner, Durham Jones & Pinegar, the fourth-largest law firm in Utah.

Adding Davis Brown to the Dentons platform means the firm will have offices in 39 U.S. cities, according to Dentons. The firm has not set an effective date for the combination.

Dentons' strategy is partly inspired by the reach and scale of the Big Four accounting firms – Deloitte, EY, KPMG and PwC – all of which have more offices in the U.S. than any traditional law firm, including Dentons, the global firm has said.

Dentons kicked off its U.S. expansion plan in October 2019 when it announced that it would combine with Indianapolis-based Bingham Greenebaum Doll and Pittsburgh-based Cohen & Grigsby.