[2] The county is east of the Mexico–United States border and is named for Colonel José Antonio de Zapata, a rancher in the area who rebelled against Mexico.

The South Texas Oil Boom included wells drilled in Zapata County in the early 1920s through the work of Laredo industrialist Oliver Winfield Killam, a Missouri native who once served as an Oklahoma state legislator.

[3] It is located in the Rio Grande Valley, on the shore of Falcon International Reservoir.

It was previously linked to Mexico by an international bridge, but this was flooded when the Falcon Dam and reservoir was built.

As of the 2020 United States census, there were 13,889 people, 4,689 households, and 3,254 families residing in the county.

[11] In the majority of U.S. presidential elections, Zapata County supported Democratic Party candidates.

However, on three occasions, it gave record-setting margins to Republican presidential nominees, when it delivered the highest percentage of the vote of any county in the nation to them.

The third and final time was in 1912, when it again gave then-incumbent President Taft 80.9% with it being his best county in the nation, but against the state and nation's preference for the Democratic victor, Woodrow Wilson (in the popular vote, Taft only received 9.5% statewide and 23.2% nationwide).