Southern Railway System DESCRIPTION: freight railroad serving a 10,000-mile route in 13 states from Washington south to New Orleans, from Cincinnati south to Jacksonville, and to Memphis and St. Louis (NYSE, P). FOUNDED: 1894 TOP EXECUTIVE: Harold H. Hall, president and CEO.

The Southern Railway has long been noted as one of most efficient and profitable railroads in the country. It serves customers from Washington South to Jacksonville, Fla., and west to Memphis and New Orleans. Galvanized in part by the creation of the CSX Corp.--a combination of its long-time rival Family Lines and the Chessie System that links the South with the industrial Midwest in one giant rail system--Southern and the Norfolk & Western Railway System decided to merge. The Interstate Commerce Commission approved the merger March 25, but the formal date for the marriage of the country's two most profitable railroads still is uncertain, although expected by summer.

The merged system--whose 16,151 miles of track will make it the nation's fourth biggest railroad--will have to take off after CSX, which has been making inroads into traffic carried by Southern and N&W. Southern, like other railroads, feels the impact of the recession. But the railroad recorded record profits in 1981 despite a decline in freight traffic.

USAir DESCRIPTION: Domestic passenger airline whose routes throughout northeastern and midwestern states have expanded under deregulation to include Arizona, Texas, Florida, Louisiana and other southern states. It also flies to two provinces of Canada. The company's headquarters is at National Airport. (NYSE.) FOUNDED: 1937 TOP EXECUTIVE: Edwin I. Colodny, chairman and president.

USAir posted earnings of $51.1 million in 1981, down just $9.3 million from 1980's record profits, a good showing given the adverse conditions that dominated the second half of the year for the airline industry: the deteriorating economy and the strike and firings of the air traffic controllers. Most airlines lost money last year. USAir carried 13.5 million passengers in 1981, down 6 percent from 1980. Its revenue passenger miles--one paying customer flown one mile--fell one percent to 5.5 billion. Revenues for 1981 were $1.1 billion, up 14 percent from $971.8 million in 1980, while expenses grew 19 percent.

Last year, USAir completed work on a new computer center in Fairfax and a new maintenance facility in Pittsburgh. The airline also added 15 gates in a newly completed concourse in Pittsburgh, its major connecting complex. USAir has begun facing competition on a few routes from the new lower cost, lower fare airlines.

The company's ability to maintain an upward trend in revenues in 1982 will be affected by the timing of an economic recovery and the continued impact of federal airport restrictions, shareholders were told in the 1981 annual report.