Through land use / plat maps, what were the borders of the Seattle
pioneer M. Harwood Young?s property on north Beacon Hill, in Seattle,
Washington between his arrival in 1889 and his death in 1913?  Only
including Beacon Hill, and no other property owned by M. Harwood Young
in the Seattle area in the given time range.

Here's a clue, at a minimum this is an excellent place to start.

UW Libraries Catalog
http://catalog.lib.washington.edu/search/X(washington+or+oregon+or+idaho+or+british+columbia)+and+(plat)&searchscope=6&b=sc%20%20%20&SORT=D&Da=&Db=/X(washington+or+oregon+or+idaho+or+british+columbia)+and+(plat)&searchscope=6&b=sc%20%20%20&SORT=D&Da=&Db=/49%2C60%2C60%2CB/browse
Note, there are 5 pages, you are linked to page 5.

Thank you, Cynthia!  Indeed, a place to start, until I can actually
get up to Seattle to peruse what has turned up so far!

Thanks beaconhill,

I happen to live in Seattle and am aware of this library, and the
archives.  I've printed a copy of your question and I'll put it in the
glove box of my car. When I get to the U-District next, I'll stop in
and look it up for you. No idea how soon that may be, but even if it's
over 30 days (question expires then), I can comment to let you know
what I found.

Thank you, Cynthia!  I am still learning Answers.Google and have been
making myself crazy attempting to rate your COMMENTS.....sigh.  My
father was a doctor at the Public Health Service / Pac Med until 1971
and I grew up on the grounds.  My curiosity stems from seeing VERY
little information, particularly pictures, as to the building of the
hospital up to 1933.  Via Seattle Now and Then and Paul Dorpat I have
some great pictures of the Dearborn St. bridge, but that is all.... 
Wanted to see how much of M. Harwood Young's property became Public
Health Service property.  THANK YOU!  (5 star comments from you so far
hee hee)