What do these cities have in common
Atlanta Cleveland Dayton Hartford Jacksonville New Haven Newark
Norfolk Philadelphia Phoenix

Hello augie205,

They are all towns in New York state.  (On other sites, this riddle is
posed as "What do the following ten places have in common ...," or
simply as what "commonality" these names have.)

I have confirmed this answer by searching for these places in New York
on this database:

"Geographic Names Information System (GNIS): Query Form For The United
States And Its Territories"
U.S. Geological Survey 
http://geonames.usgs.gov/pls/gnispublic

- justaskscott


Search strategy --

Searched on Google for:

"Atlanta Cleveland Dayton" Hartford Jacksonville New Haven Newark
Norfolk Philadelphia Phoenix

[I knew about the Geographic Names Information System from a previous
Google Answers question.]

Great answer Thanks

They all start with the letter "P", except Atlanta, Cleveland, Dayton,
Hartford, Jacksonville, New Haven, Newark and Norfolk.

They all have a professional baseball team, either in Major League
baseball or one of the minor league teams (Dayton, Hartford,
Jacksonville, New Haven, Newark and Norfolk).

Best regards,

Omnivorous-GA

They are all unimportant cities located in the U.S.

"What do these cities have in common
Atlanta Cleveland Dayton Hartford Jacksonville New Haven Newark
Norfolk Philadelphia Phoenix"

Just as a matter of clarification, are you refering to Jacksonville in:
Florida, Alabama, N.C., S.C., Illinois, Ohio, Georgia, Texas,
Mississippi, Tennessee, Kentucky....?

Oh, and about Dayton:
Texas, Ohio, Kentucky, Tennessee, Indiana, Illinois, Michigan,
Minnesota, Nebraska....?

Scott's answer is probably what is being sought, but the names of the
ten cities also have in common that they do not contain the letters  B
G M Q U Z.

Bad Gorillas May Quickly Upset Zoologists.

I am a pedant when it comes to New York State geopragphy.  According
to the Census Factfinder
(http://factfinder.census.gov/),

Atlanta does not exist (USGS calls it a "populated place")
Cleveland is a village, not a town
Jacksonville does not exist (USGS lists two "populated places")
Newark is a village, not a town (there is a town named Newark Valley)
Phoenix is a village, not a town

Re Nelson's comment:

I mean "town" in the popular sense of a named, populated community
that lacks the status of "city."

According to the US Postal Service, Atlanta, NY 14808, and
Jacksonville, NY 14854, exist:

"ZIP Code Lookup -- By City"
United States Postal Service
http://zip4.usps.com/zip4/citytown_zip.jsp

See also:

Results for: "ny 14808"
Google
://www.google.com/search?q=%22ny+14808%22

Results for: "ny 14854"
Google
://www.google.com/search?q=%22ny+14854%22

Sorry to be such a putz.  Yes, these places do exist.  And of course,
the popular conception of "town" is perfectly acceptable, even if it
does not coincide with New York's legal definition.

(As an aside, the post office is a pretty bad arbiter of geography. 
For example, they would have us believe that Sarah Lawrence College is
in Bronxville, but it's really in Yonkers.  And the Scarsdale postal
zone stretches beyond the municipality's borders.)