Big Island Vector data

the island has 1400 km of county-maintained road, 46 km unpaved and 1354 km paved, with over 118,000 registered cars [source]

apparently in 1995, many or all of the transportation DLGs were re-done by the USGS
the differences from the previous version (1981 map production) is major
there is a huge number of new roads and cleaned up topology - but there are also hundreds of dirt roads missing, which were present in the 1981 data
the USGS now provides both the old and new (1981/1995) datasets in SDTS, and the higher file number is the newer file (e.g. 852225 vs. 1384033)

free DLG-O data for the island is available
- in 30-minute by 1-degree regions, each split into 8 15-minute regions
- file names H73, H82, H91, H92, H93, H94, HZ1
all but the western tip of the island is in UTM zone 5
problems with the free data
- lots of roads are missing
- roads have lot of bogus "crooks" and angles
7.5-minute DLG files are also available from the USGS ESIC
- 81 files to cover the island, cost around $600, now much cheaper due to price reductions
- ordered and received in 1997 - it's much cleaner, more complete and accurate
- free, 30-minute DLG
  cheap, 7.5-minute DLG
- even with UTM, there's a datum issue - the DLGs claim to be NAD27 (although they are actually OHD, Old Hawaiian Datum), the 30m DEMs are Old Hawaiian Datum, and the 10m DEMs are NAD83

Highway markings
- center of road always indicates passing status
- three kinds of reflectors
- older, less-maintained roads usually have only a single dashed line in the center, with no edge markings
Road signs
- elevation signs are at each 500m contour boundary on major highways
- highways have number signs

as the DLG show, there are virtually no lakes or ponds; only a few artificial reservoirs
streams appear only where the land is old and the rainfall is high, and most of them are only temporary, during rainfall

Tax maps provide the shape of the property and outline the adjacent lots and roads
Each page is referenced by a Tax Map Key (TMK)
As of 2004 the county website put Tax Map Data online, but only as TIF scans, not geolocated in any way.
2005.02, discovered on the State GIS website that there are now TMK Parcels - Hawaii County, 2003 which is a georeferenced SHP file in NAD83 (!) These were apparently produced by GDSI Hawaii (owned by ESRI) then handed off to the County government in 2003. Some notes comparing the 2003 TMK to the USGS transportation DLG files.
2005.03.07, discovered the County of Hawaii's Real Property Tax Site which has an excellent full database for every property on the island, including (raster) renderings of parcel boundaries
As of 2008, the State website is TMK Parcels (All Islands) - Downloading Site

As of 1998, County of Hawai‘i tax maps are reportedly still maintained with ink on linen.. some of the maps now online have date stamps which imply they were last updated in 1984 (!) Printouts are available in some local public libraries.
4/99 Called the County Planning Office and learned there was an electronic version of the real estate information made in the 1990s
- the company is First American Real Estate Solutions
- the county provides the paper documents to the company, the company scans them and re-sells them, by county, on CDROM, along with a Windows-based program for viewing and searching the information
- cost is around $1000 per county, with "assessor maps" costing around $300 more
- the fee is annual; information is updated each year
- however, the "assessor maps" are just raster scans, there is no boundary vector data or geographical coordinates
also available was georeferenced by LandInfo Parcel Tax Maps
- are available as 300 dpi TIFF files
- includes individual tax identification numbers, acreage, street names, and other features
- they are sold for $5/map, which is $32,345 for all 6,482 maps in Hawai‘i County
- georeferenced!!
- unfortunately you must buy the entire county