In Borax Consolidated v. Los Angeles, 296 U.S. 10, 80 L. Ed. 9, 56 S. Ct. 23 (1935), the City of Los Angeles brought suit to quiet title to land claimed as tideland of Mormon Island located in Los Angeles Harbor. Borax, 296 U.S. at 12. The United States Supreme Court held that the tideland extends to the high-water mark, which is "the line of high water as determined by the course of the tides." Borax, 296 U.S. at 22. To determine the exact location of this line, the Supreme Court adopted a standard based on long-term averaging of daily high waters. Borax, 296 U.S. at 26-27. Consequently, the Supreme Court concluded that mean high tide, calculated by averaging the daily high tides over 18.6 years as defined by the U.S. Coast and Geodetic Survey, should be used to determine seashore boundaries for federal grants under common law. Id. Although the Supreme Court specifically left to individual states where to best locate state tidal boundaries, Borax is instructive in showing how federal courts determine seashore boundaries for common-law grants.