Elevation

Go to the 3DEP Products and Services Web page to find information about elevation data.
There are a number of Mac programs that will read elevation files. A few open source programs are:
The elevation point query service returns elevations from the 1/3 arc-second DEM dataset in The National Map.
All 3DEP products available through The National Map are in the public domain and may be used without restriction. The USGS does request that proper credit be given when used for redistribution, resale, presentation or publication.
Yes. To maintain consistency, original seamless elevation data distributed from USGS are only produced on NAD83 with a geographic coordinate system.
The USGS distributes source DEMs, received after March 2014, in their original project resolution (OPR) and horizontal coordinate system.
Elevations are pixel-centered in raster datasets, which are used by most GIS applications.
There are frequently multiple sources of elevation data held by the USGS that cover a given geographic location.
Graphics showing 3DEP product availability and recent updates can be found on the 3DEP Product Availability Web page. Areas containing recent updates are refreshed monthly.