It would not be stretching the truth to say that the mature traveler helps keep the boats of the Delta Queen Steamship Co. afloat.
This June, the company is adding a new steamship, the America Queen, to its fleet that includes Delta Queen and Mississippi Queen.
"Steamboatin' Country" is that part of mid-America that Mark Twain often wrote about. A sampling of historic cities on these routes include Chattanooga, St. Louis, Little Rock, Vicksburg, Baton Rouge and Hannibal.
The routes of the company's scheduled sailings are divided into four regions: The American South, which includes the Mississippi River below Memphis; Crossroads of America, from the Arkansas River Delta to Tulsa, Okla., and up to St. Louis; America's Heartland, from St. Louis to St. Paul, Minn., and Wilderness Rivers--the Ohio, Tennessee and Cumberland.
In addition to regional itineraries, there are theme voyages for passengers who want to hear prominent speakers in such topics as sports, history, cooking or music.
Scheduled theme cruises on all boats for 1995:
* April and May--a series of Kentucky Derby vacations ranging from four to nine nights.
* June and July--the Great Steamboat Race commemorating the historic race between the Robert E. Lee and the Natchez in 1870.
* July and August--All-American Baseball Cruises with baseball greats such as Bob Feller, Willie Stargell and Bill Madlock.
* June through August--The Good Old Summertime cruises, which include barbershop quartets and sing-alongs, scavenger hunts, a slumber party, nature walk and a boardwalk carnival.
Other theme cruises include:
* History of the Civil War.
* Music of the River with experts who will conduct courses and discussion on jazz, blues, ragtime, folk, Cajun, rockabilly, bluegrass and country.
* World War II cruises with wartime veterans, plus entertainment from the '40s and dancing to big-band music.
Prices for Steamboatin' River Cruises vary from $163 to $588 per night, depending on the stateroom category and the length of the cruise, which may range from three to 15 nights. Prices include shipboard entertainment, meals, lectures and activities. For a brochure, call the Delta Queen Steamboat Co. at (800) 543-1949, or your travel agent.