The National Flood Insurance Program began in 1968. The federal government subsidizes flood insurance through the program in participating communities, which are mostly cities, towns and counties. Properties with mortgages held by federally backed banks must have flood insurance if the property is in an area called a Special Flood Hazard Area. In this case, people generally say a property is "in a flood zone".
FEMA creates the flood maps by county and releases them on their website. Usually several counties are updated each day. Several different maps must be checked to collect all the data that insurance companies require. The most commonly used fields are:
dfirm_id: This is the flood insurance rate map id. The
dfirm_idis usually of the for XXYYYC, where XX is the state fips code and YYY is the county fips code.
fld_zone: This is the flood zone, which is generally an A,X or V followed by another letter or number. A and V zones are Special Flood Hazard Area zones.
sfha_tf: This field is either True or False and states whether or not the location is in a Special Flood Hazard Area
zone_subty: This field is a description of the flood zone.
eff_date: The date at which the current flood map for the location became effective.
panel: This is the panel number or section of the flood map that the data is drawn from.
comm_no: The community number. This is necessary to check community participation.
comm_name: The community name.
comm_part: This field is either True or False and states whether or not the community participates in the National Flood Insurance Program.
FEMA continuously updates this data for the 3,000+ counties in the US. National Flood Data keeps track of all of these updates and maintains a database to offer the data by API so that our customers can automate their data pipelines.