Resulting map from interpolate_to_grid

[DaveJ83]

I have been playing around with interpolate_to_grid. I went to the metpy doc site and downloaded the notebook at the bottom of this link
https://unidata.github.io/MetPy/latest/examples/gridding/Wind_SLP_Interpolation.html#sphx-glr-examples-gridding-wind-slp-interpolation-py

I haven't been able to figure out how to make the data on the resulting map only show inside the outline of the country. Any help is appreciated.