import arcpy, os

### Set directory
arcpy.env.workspace = ...
arcpy.env.overwriteOutput = 1

### Define inputs
yellow = "symbology/yellow.lyr"


        # Set map document
        mxd_city_year = arcpy.mapping.MapDocument(r"...blank_map.mxd")
        DF = arcpy.mapping.ListDataFrames(mxd_city_year)[0]

        # Add layers
        arcpy.MakeFeatureLayer_management("states/continental_US.shp", "us")
        basis = arcpy.mapping.Layer("us")
        arcpy.mapping.AddLayer(DF, basis, "AUTO_ARRANGE")
        arcpy.ApplySymbologyFromLayer_management(basis, yellow)

# Save map
mxd_city_year.saveACopy("thresh_" + city + "_" + year + ".mxd")