La Porte's first business was the Seureau Mercantile Store, which opened in March 1892 at the corner of Main and Third Streets, with living quarters upstairs as was customary. Owned by Mr. and Mrs. Eduoard P. Seureau, the store followed Mr. Seureau's purchase of the property on the Harris County Courthouse steps in Houston on New Year's Day in 1892. Investors had promoted the New Gulf City widely across the Midwest, New York, and at the Chicago World's Fair, and Mr. Seureau anticipated that incoming settlers would need hardware, dry goods, and groceries, so he quickly built the store before excursion trains from the Midwest arrived. Mr. Seureau also became La Porte's first postmaster. The original building burned in December 1892 during one of La Porte's many fires, a new store was erected on the same site using exactly the same plans, that second store burned in the 1915 fire that destroyed much of downtown, and a third store built on the site to the same plans stood until its demolition in 1980.