I'm trying to make a topo map for Garmin based on USGS and Tiger data. But I I don't have forest and swamp data.
Nule and others: Please provide area of interest in your posts. Available data can differ greatly by area.
Nule: Swamp/marsh is coded H2025 in the TIGER data. The forest/woodland layer is the most difficult layer to digitize. I am not aware of a source which digitized this info on a National level. Some State GIS office, etc. may have done so.
if you look at many (most?) of the maps on this site, no wetlands are shown.
past time for new glasses
I use GM and dbase and include NHD codes 46600, 46601 and 46602 (State topos) and TIGER H2025 (regional planimetric) - wetlands/swamp/marsh.
As the author of most of the State topos, I find (IMHO) that statement very inaccurate and misleading.
Also consider the differences in:
Definition of wetland as used by USGS and others for printed map products
versus that used by biologist in the National Wetland Inventory database
versus what can be accurately classified with a 30m pixel size in the LULC data set.
Differences in age of the source data.