HOUSTON — A 27-year-old Houston woman who emigrated to the U.S. in 2005 has been elected the top executive of the nation's third-largest county.

Democrat Lina Hidalgo's win in Texas makes the Colombia native the first Latina county judge in Harris County. She is also one of youngest big-county leaders in the U.S.

Her narrow victory Tuesday night ousted a popular 10-year Republican incumbent who steered the diverse county of 4.7 million people through Hurricane Harvey and other disasters along the Texas coast.

It was one of the biggest victories for Democrats in Texas, where Senate challenger Beto O'Rourke energized his party like no other candidate in a generation.

O'Rourke lost by fewer than three percentage points to Republican Sen. Ted Cruz.

Hidalgo ran on issues of flood control and criminal justice reform.