I would like to know if it would be possible to find Parcel boundaries for counties in the US through Open Source resources (free). I am particularly interested in parcels for counties in the state of Florida. Counties of Hillsborough, Polk, Pasco,Pinellas,Osceola,Lake and Manatee.
check out the Florida Dept of Revenue FTP site here: ftp://sdrftp03.dor.state.fl.us/Map%20Data/
As Barry Carter explained, parcel data in the US is generally maintained at the county level. Unfortunately this means you usually have to download it from a separate source for each county. Here's a quick explanation of how to find parcel data downloads.
Usually the parcel data can be found by searching for the county auditor's website. Be sure to include the name of the state in your search, as many county names are used in more than one state. Go to the auditor's website and look for a link for "downloads," "data" or similar. If the website is poorly organized you may need to use the search function. If the website is extremely poorly organized, you may need to return to google and refine your search (with terms like parcel, data, GIS, shapefile, download, etc). Repeat for all counties in your list.
For example, when I Googled "florida hillsborough county auditor," the very first search result was the website of the Hillsborough County Property Appraiser, which has a link to a Downloads page where you can get GIS data. You probably want the file called
parcel_03_20_2020.zip but you will need to download it to be sure. It turns out Florida calls the official responsible for maintaining parcel data a "property appraiser" instead of a "county auditor," but I was still able to find the relevant websites with the search term "auditor."
- Hillsborough County Property Appraiser GIS Data
- Polk County Property Appraiser GIS Data
- Pasco County Property Appraiser GIS Data
- Pinellas County Property Appraiser GIS Data
- Osceola County Property Appraiser GIS Data
- Lake County Property Appraiser - As far as I can tell, parcel data is not available as a free download for Lake County. I only did a cursory search; you may have better luck if you spend some more time looking around their website. The page I linked to has has contact information where you can request data, as well as a data price list.
- Manatee County Property Appraiser GIS Data