No method matching iterate(::Shapefile.Polygon)

Specific Domains Data
1

I want to know if a lat/long coordinate is inside a specified set of US states. I downloaded a shapefile for the US states from the Census Bureau. Suppose my coordinate is (38.4511,-80.5194), and I want to know if this coordinate is in the states of PA, NY, or NJ.

My current code is the following:

using Shapefile, GeoInterface, GeometryBasics
state_table = Shapefile.Table("path/to/cb_2018_us_state_500k/cb_2018_us_state_500k.shp")

## data frame for selecting states
state_DF = DataFrame(state_table)
keep_states = ["NJ", "PA", "NY"]
state_DF = filter(:STUSPS => x -> x in keep_states, state_DF)

function is_in(point::GeometryBasics.Point, polygon)
    return in(point, polygon) 
end

for i in 1:3
    if is_in(Point(-80.5194, 38.4511), state_DF[i,1])
        println("The point is inside ", state.attributes["STATE_NAME"]) 
        break # Stop after finding the first matching state
    end
end

Then, I get the following error:

ERROR: MethodError: no method matching iterate(::Shapefile.Polygon)
Closest candidates are:
  iterate(::Union{LinRange, StepRangeLen}) at range.jl:872
  iterate(::Union{LinRange, StepRangeLen}, ::Integer) at range.jl:872
  iterate(::T) where T<:Union{Base.KeySet{<:Any, <:Dict}, Base.ValueIterator{<:Dict}} at dict.jl:712
  ...

How can I accomplish my task? I’ve tried bypassing this error for a bit now.