Early settlers in the eastern and central areas of San Patricio county faced difficulty traveling across Corpus Christi Bay to Corpus Christi, the main center for trade. The Reef Road, which according to local tradition was discovered by indians, was the shortest and most favored route. Consisting of oyster shell reefs close to the water's surface, the road was passable only at low tide. Construction of the railroad (1887) and first causeway (1915) across the bay signalled a decline in usage of the road, but it remains an important part of the county's history.