There are two primary data repositories maintained by Miami-Dade County government:
Both data download platforms contain current and up-to-date data. According to staff at Miami-Dade County government: "The plan is to ultimately replace Self Services with Open Data" (personal correspondence).
The MDC Self Services platform contains nearly 100 datasets available for free download as GIS vector shapefiles in compressed (.zip) archive format, in Computer Aided Drafting and Design (CADD) drawing (.dwg) format, and in Google Earth's keyhole markup language (.kml) format.
All shapefiles are in the North American Datum 1983 (NAD83), State Plane Coordinate System Florida East (FIPS 0901), US Feet (WKID: 2236 Authority: EPSG) coordinate reference system. Formal metadata records for most of the datasets are also available.
There are over 60 "strategic area" categories used to organize the datasets.
Browse through the categories to identify the datasets of interest to you. Once identified, a dataset can be downloaded by clicking on the "additional info..." button to the right.
A description of the feature class will appear as a separate dialog box. The dates of the most recent modification ("Modified On") and review ("Reviewed On") will be visible, as well as an html link to the metadata record associated with the feature, if available.
Within the "Additional Documents" section, one will find the three download options mentioned above: .zip, .dwg, .xml. Select the floppy disk icon beside the desired data format to initiate the download.
GIS software users should select the .zip format, which contains the dataset in shapefile format (.shp, and its other constituent file components, e.g., .dbf, .shx, .prj, etc.)
A small box will appear to indicate that the download is complete. The dataset will be downloaded to the specified file directory, or to your default download directory, depending on the settings of your web browser.
Coordinate Reference System: North American Datum 1983 (NAD83), State Plane Coordinate System Florida East (FIPS 0901), US Feet (WKID: 2236 Authority: EPSG)
The MDC Open Data platform contains all or most of the datasets available via the Self Services platform described above. However, the former offers those datasets for download in a greater number of formats.
In addition to compressed (.zip) shapefile format, Open Data permits downloading to spreadsheet (.csv) and Google Earth (.kml) too. CADD drawing (.dwg) and schema (.xml) formats are not available via the Open Data platform, as they are with Self Service.
Open Data also offers data downloads via the following application programming interface (API) formats: GeoJSON and GeoService. These formats are of particular use to developers and users of web maps and other web-based geospatial services.
It is also possible to open a dataset directly into ArcGIS.com from the Open Data platform. The following images illustrates the Miami-Dade County Commission District polygon layer opened directly in ArcGIS.com.
Another useful feature available through this platform is that one can also download filtered subsets of the particular dataset in question.
All shapefiles are in the World Geodetic Survey (WGS) 1984 (WKID: 4326 Authority: EPSG) coordinate reference system. Formal metadata records for most of the datasets are also available.
The Open Data platform comes with several other additional features as well, including, among others:
Users can search for datasets using one of the 17 pre-defined categories, or simply by entering a keyword in the search bar at the top of the page. Alternatively, one can also select the "search within map" option and search by the spatial extent of the layers.
Coordinate Reference System: World Geodetic Survey (WGS) 1984 (WKID: 4326 Authority: EPSG)