Lavaca is a city in Sebastian County, Arkansas, United States. It is part of the Fort Smith, Arkansas-Oklahoma Metropolitan Statistical Area. The population was 1,825 at the 2000 census.
Lavaca is located at 35°20′12″N 94°10′36″W / 35.33667°N 94.17667°W / 35.33667; -94.17667 (35.336657, -94.176776).
According to the United States Census Bureau, the city has a total area of 2.2 square miles (5.6 km²), all of it land.