I know where I was 50 years ago. I was watching a big man with a famous grin as he sat signing Tennessee Valley Authority legislation that was to do as much as any document to bring the United States into modern times.
It was in the middle of Franklin Roosevelt's unprecedented ''100 Days.'' It was still uncertain whether there would be evolution or revolution. Twice before , Congress had passed a bill to bring a social experiment to a 41,000 -square-mile impoverished watershed of the Tennessee River. Both Calvin Coolidge and Herbert Hoover had vetoed it. President Hoover had shuddered at what he saw as creeping socialism:
''I hate to contemplate the future of our institutions, of our country,'' he told Congress, ''if the preoccupation of its officials is to be no longer the promotion of justice and equal opportunity, but is to be devoted to barter and the market. This is not liberalism, it is degeneration.''
On the other side was Sen. George Norris, a progressive maverick from Nebraska, with a perpetual look of surprise and wistfulness, who thought natural resources should be used for the immediate good. Woodrow Wilson had pushed Alabama's Muscle Shoals as the site for nitrate production in World War I.
The Tennessee River in that area drops 137 feet in just 37 miles. The potential for cheap electricity existed in a backward area of kerosene lamps. By contrast, Senator Norris found on a visit to Canada that under the hydro program there, 334 kilowatt hours cost $3.25, while the same power in Nashville, Tenn., cost about $40. He wanted FDR to intervene immediately. FDR said he would.
Fifty years ago, America was at the bottom of the worst depression of modern times. This reporter accompanied the Roosevelt campaign party in 1932. There was one tremendous sunset above the prairie at McCook, Neb., when FDR and Norris, before a crowd of 16,000, jointly outlined what they hoped to accomplish.
''As soon as the rush of emergency legislation is over,'' FDR wrote Norris eight days after his inauguration, ''I hope you will come in and have a talk with me about Muscle Shoals, and the Tennessee Basin Development.''
What developed was far bigger than the original Muscle Shoals project. It was breathtaking. It would have ''the broadest duty of planning,'' said FDR. In short, ''this power development of war days leads logically to national planning for a complete river watershed involving many states and the future lives and welfare of millions. It touches and gives life to all forms of human concern.''
To George Norris it was almost unbelievable - ''the most wonderful and far-reaching humanitarian document that has ever come from the White House.''
The United States was propelled into a new era by the extraordinary 100 Days. A Roosevelt supporter, Stuart Chase, in an article in the New Republic magazine, argued that the time had come for more public planning like Europe's: ''A New Deal For America,'' he called it. This combined Theodore Roosevelt's Square Deal and Woodrow Wilson's New Freedom. FDR cried it out - the New Deal.
Hoover denounced it. It proposed an autonomous government development plan for an area three-fourths the size of England, including 28 dams. Historians Samuel Eliot Morison and Henry Steele Commager, summing it up in their ''The Growth of the American Republic'' (1937), called it ''an almost complete reversal in policy and political philosophy. . . . The change involved . . . a candid acceptance of socialism in the realm of public utilities and a commitment to the experiment of a planned economy.''
Fifty years later in 1983 America takes TVA for granted. There will be anniversary celebrations on May 18 at Knoxville and Chattanooga and Muscle Shoals. Almost forgotten are Hoover's shudders at creeping socialism in his veto of Norris's proposed TVA program on March 3, 1931. Today the government is to one degree or another involved in activities ranging from nuclear power to satellite communication.
Today President Reagan says America may have pushed federalism too far and corrective processes are visible. The process of government, in a word, is continuous.