In the 1970s, you could look through most any airline schedule and find lots of multi-stop flights. The Civil Aeronautics Board controlled all aspects of intercity airline service, including setting fares and awarding nonstop service on routes around the country. While larger cities benefitted from nonstop service to other larger cities, smaller cities and towns were most often served via multi-stop service or "milk runs".
http://public.fotki.com/Seat2A/2011-autumn-perigri/zzz-sea-pdx-jpg.html
Seattle to Portland Schedule from March 1968
Government subsidies made it possible for airlines to provide service to smaller communities like Lamar, Colorado or Cheyenne, Wyoming. Flights to cities like these were often part of a larger service to other cities in the region. Thus it was possible to find four-stop service between Seattle and Portland via TIW, OLM, HQM and AST (Tacoma, Olympia, Hoquiam and Astoria) on Hughes Airwest.
http://public.fotki.com/Seat2A/2011-autumn-perigri/mso-den-nov-1970.html
Missoula to Denver Schedule from November 1970
Frontier operated eight-stop Convair 580 service between Missoula and Denver (MSO-BZN-BIL-COD-WRL-RIW-CPR-LAR-CYS-DEN).
http://public.fotki.com/Seat2A/2011-autumn-perigri/ord-sea-nov-1970.html
Chicago to Seattle Schedule from November 1970
One of my favorites was Northwest #105, a seven-stop 727 flight between Seattle and Minneapolis routing ORD-MSP-FAR-BIS-BIL-GTF-GEG-PDX-SEA. Through passengers wouldn't go hungry with breakfast, lunch and a snack served enroute.
http://public.fotki.com/Seat2A/2011-autumn-perigri/jfk-msy-nov-1970.html
New York to New Orleans Schedule from November 1970
Finally, who wouldn't want to spend nine hours aboard National 493, a stretch 727 traveling between New York and New Orleans via DCA, ORF, CHS, JAX, TLH, PFN, PNS and MOB. It's still faster than the bus and you'd be served three snacks and a lunch along the way. Real diehards could book this as a nine stop flight to Houston and have another snack enroute.
These days most of the government subsidies are no longer offered, so citizens of cities like Olympia or Cheyenne have to drive to the closest big city airport such as SEA or DEN. Many smaller communities now enjoy nonstop service from airline hubs via the regional operations of most major airlines. A good example of this would be American Eagle's nonstop ERJ-145 service from Chicago to Manhattan, Kansas.
Some of the last remaining jet operated "milk runs" in North America are offered by Alaska Airlines on its flights to communities along Alaska's southeastern panhandle. Many of these towns don't have the population to support a profitable daily nonstop service from Seattle or Anchorage, so they are served via a single flight that serves many of them. My personal favorite is Alaska #65, which departs Seattle for Juneau via Ketchikan, Wrangell and Petersburg. AS 65 actually continues on to Anchorage, but Alaska will generally not sell SEA-ANC space on this flight. My flight down to Juneau this afternoon makes stops in Cordova and Yakutat before visiting Juneau and continuing on to Seattle.