USA Topo downloads no longer available for Global Navigator 4.5
Article GN13198, May 18, 2015
Product discontinued, downloads not available for pay or for free.
The USA Topo product has been discontinued and will not be made available again. No further data downloads of topographic map tiles at any scale are possible in Global Navigator 4.5 or Marine ENC 4.5. Map content already downloaded and cached in the software will continue to be viewable but cannot be ported to another computer with a new install of software.
You may find other sources of USA topographic maps in file formats supported by Global Navigator (see the Help resourcs in the software for map importing support). For example, you may be able to get GeoTIFF files from the US Geological Survey and these should be suitable for Global Navigator.