NAIROBI (Reuters) - Kenya's highways authority and U.S. infrastructure investment manager Everstrong Capital have signed a $3.6 billion agreement to build a 440 km (273 miles) highway between the capital and port city Mombasa, the company said on Thursday.

A bigger highway between Mombasa and Nairobi has been on the wish list of successive governments aiming to ease congestion on the busy road to and from the port.

"The project anticipates attracting investments totalling $3.6 billion, sourced from international investors, development agencies, pension funds and an exceptionally large number of Kenyan private investors," Everstrong said in its statement.

The deal coincides with Kenyan President William Ruto's visit to the United States, the first such state visit by a leader from Sub-Saharan Africa since 2008.

(Reporting by George Obulutsa; Editing by David Goodman)