|source = PGS|
|Prototype Global Shoreline: coastline data from the US National Geospatial-Intelligence Agency|
|Used on these elements|
|Status: in use|
|Tools for this tag|
Since high-quality imagery now available nearly globally, replacing the crude PGS coastlines is strictly encouraged. In 2016, approximately 25% of natural=coastline ways had source=PGS, 2019 it was 17 %, 2020 it was down to 10 %. As of July 2021 the PGS prevalence is approaching 5%.
Although this tag is mainly about ways, it also appears on many nodes. Years ago it was typical for imports to put metadata tags, such as source=*, on all nodes even if those nodes are merely parts of ways. This import tagging scheme became less popular after the bloated TIGER node tags, introduction of changeset tags, and recommendations for dedicated import user accounts (see import guidelines).