When rendering with Mapnik, you have an input projection and an output projection. The input projection is what your data is in, and has to be given in the `<Layer>` element. The output projection is what you want your map to be in, and is usually given in the `<Map>` element (but some client programs e.g. nik2img.py allow you to override that). You likely want your map in Google Mercator projection so your `<Map>` element <Map bgcolor="transparent" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs +over"> looks ok (but try writing srs="+init=epsg:3857" which should also work and is clearer). Your `<Layer>` elements claims that the source data is in Mercator as well, but it isn't; this will lead to distorted rendering. Your source data, raw latitudes and longitudes from OSM, is in EPSG:4326, so you'll need something like this: <Layer name="highways" status="on" srs="+epsg:4326"> srs="+init=epsg:4326">

When rendering with Mapnik, you have an input projection and an output projection. The input projection is what your data is in, and has to be given in the `<Layer>` element. The output projection is what you want your map to be in, and is usually given in the `<Map>` element (but some client programs e.g. nik2img.py allow you to override that). You likely want your map in Google Mercator projection so your `<Map>` element <Map bgcolor="transparent" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs +over"> looks ok (but try writing srs="+init=epsg:3857" which should also work and is clearer). Your `<Layer>` elements claims that the source data is in Mercator as well, but it isn't; this will lead to distorted rendering. Your source data, raw latitudes and longitudes from OSM, is in EPSG:4326, so you'll need something like this: <Layer name="highways" status="on" srs="+epsg:4326">

When rendering with Mapnik, you have an input projection and an output projection. The input projection is what your data is in, and has to be given in the `<Layer>` element. The output projection is what you want your map to be in, and is usually given in the `<Map>` element (but some client programs e.g. nik2img.py allow you to override that). You likely want your map in Google Mercator projection so your `<Map>` element <Map bgcolor="transparent" srs="+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs +over"> looks ok (but try writing srs="+init=epsg:3857" which should also work and is clearer). Your `<Layer>` elements claims that the source data is in Mercator as well, but it isn't; this will lead to distorted rendering. Your source data, raw latitudes and longitudes from OSM, is in EPSG:4326, so you'll need something like this: <Layer name="highways" status="on" srs="+epsg:4326">