I'm a newbie to the GIS world and I'm trying to convert a shapefile to GeoJSON for use in Mapbox.
When I view the resulting layer in Mapbox, most of the features appear southeast by 20-30 feet of where they should be to match up properly with the underlying Mapbox map. (View at http://blueroomdesign.net/stlv/)
How do I adjust the Mapshaper command to fix this offset issue?
Here's the command line I'm currently using to convert it:
mapshaper -i prcl.shp -proj latlon -o prcl_out.geojson precision=0.000001
Some of the information from running the Mapshaper Info command on the shp file (below) looks relevant but I'm not quite sure how to interpret it or correct for it in the conversion process.
Layer name: prcl Records: 127,748 Geometry Type: polygon Bounds: 551318.459568 982946.566771 592589.572865 1070913.306444 Proj.4: +proj=tmerc +x_0=152400.3048006096 +lon_0=-90.5 +k_0=0.9999333333333333 +lat_0=35.83333333333334 +to_meter=0.3048006096012192 +ellps=clrk66
Here's a link to the original shapefile zip: St Louis Parcel Data