Of course America has changed in superficial, technological ways since the mid- to late 19th century—for example, you can’t take to the open road on foot if it’s an Interstate—but the main difference is that America was still forming, still establishing its “personality”, still working out the practical ramifications of its Constitution, still an agricultural economy.  Today, America spends much of its energy and resources on international matters—global economics, defense and diplomacy, cultural adjustments—and agriculture has become big business, and the internal balances are much more constant and stable.  The other major difference between Whitman’s America and ours is the diminution of real human contact; the obvious example is the electronic contact replacing physical contact or even voice contact; subtler but just as important is the distance we keep between ourselves and strangers—children are taught not to talk to strangers, for example.  There is an incident in Whitman’s biography that illustrates this change:  Whitman saw a child crying on the sidewalk, and he picked him up and put him on his lap, where he fell sound asleep.  (Remember how Whitman looked—would any bearded stranger be allowed to put a strange child on his lap in a big city today?)  This anecdote is emblematic of how America has lost its trust in humanity.