An expanded definition of Heath Center and Gill’s Riverside Village historic districts have been nominated by state Secretary of State William Galvin to the National Register of Historic Places, his office announced Tuesday.

Both nominations will be submitted to the National Register of Historic Places at the National Park Service in Washington, D.C., for final consideration and designation.

“Inclusion of Gill’s Riverside Village in the National Register will help to preserve the buildings and streetscapes of this historic area,” said Galvin of the southernmost section of Gill, on both sides of Route 2.

“Expansion of the National Register boundaries of the Heath Center Historic District will help to protect additional historically significant buildings and sites that evoke the town’s rich agricultural heritage.”

Heath Center Historic District, listed in the National Register in 2007, is a civic and residential neighborhood in a predominantly rural setting. The boundary increase is aimed at adding properties located at the north and south borders of the original historic district.