Hi Jeff
Try to type these lines:

mass.map <- map("state", "massachusetts:main", fill=T)

mass.win <- owin(xrange=mass.map$range[1:2],yrange=mass.map$range[3:4] )


Indeed, using this command:
names(mass.map)

you can see that your object mass.map has different columns. Columns x and y are the coordinates of all points describing the contour lines of mass.map object.
You need to use instead the column "range" that contains the bounding box coordinates.
In details :

mass.map$range[1:2] # from 1 to 2 for the x range

mass.map$range[3:4] # from 3 to 4 for the x range


Cheers



 
Dr. Francesco Carotenuto (Ph.D.)
Department of Earth Sciences
Federico II University
Largo S. Marcellino 10,
80138 NAPLES (ITALY)
http://francesco-carotenuto.blogspot.it/
http://3dpaleontology.blogspot.it/ 
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