Matamoros, city, northernTamaulipasestado (state), northeasternMexico. It is situated on the southern bank of theRio Grande (RíoBravo del Norte), 28 miles (45 km) from theGulf of Mexico and across fromBrownsville,Texas. Matamoros, founded in 1824, was the scene of bitter fighting in theMexican-American War and was occupied by U.S. troops in 1846. It is now one of Mexico’s chief ports of entry for tourists and for the import and export of goods. The manufacturing and commercial centre of an extensive cotton- and sugarcane-growing area, it has tanneries,cotton mills, and distilleries. Air, rail, and highway connections link Matamoros to Monterrey andMexico City. Pop. (2010) 449,815; metro. area, 489,193; (2020) 510,739; metro. area, 541,979.