---
kind: "section"
citation: "43 U.S.C. § 1312"
title: "43"
title_heading: "Public Lands"
number: "1312"
heading: "Seaward boundaries of States"
release: "119-102"
date: "2026-07-12"
url: "https://uscodex.org/usc/43/1312"
units:
  - "Chapter 29 — Submerged Lands"
  - "Subchapter II — Lands Beneath Navigable Waters Within State Boundaries"
---

# §1312. Seaward boundaries of States


The seaward boundary of each original coastal [State](/usc/43/1301.md?p=g) is approved and confirmed as a line three geographical miles distant from its [coast line](/usc/43/1301.md?p=c) or, in the case of the Great Lakes, to the international boundary. Any [State](/usc/43/1301.md?p=g) admitted subsequent to the formation of the Union which has not already done so may extend its seaward [boundaries](/usc/43/1301.md?p=b) to a line three geographical miles distant from its [coast line](/usc/43/1301.md?p=c), or to the international [boundaries](/usc/43/1301.md?p=b) of the United States in the Great Lakes or any other body of water traversed by such [boundaries](/usc/43/1301.md?p=b). Any claim heretofore or hereafter asserted either by constitutional provision, statute, or otherwise, indicating the intent of a [State](/usc/43/1301.md?p=g) so to extend its [boundaries](/usc/43/1301.md?p=b) is approved and confirmed, without prejudice to its claim, if any it has, that its [boundaries](/usc/43/1301.md?p=b) extend beyond that line. Nothing in this section is to be construed as questioning or in any manner prejudicing the existence of any [State](/usc/43/1301.md?p=g)’s seaward boundary beyond three geographical miles if it was so provided by its constitution or laws prior to or at the time such [State](/usc/43/1301.md?p=g) became a member of the Union, or if it has been heretofore approved by Congress.


## Source credit

(May 22, 1953, ch. 65, title II, § 4, 67 Stat. 31.)