guessingrows

Proc Import uses the first 20 rows of your data file to decide what kind of data each variable is. If your data is such that the first 20 rows are not enough, you can use the guessingrows option in proc import:

     proc import file='text.csv' out=out dbms=csv;
     guessingrows=300;
     run;

This is useful if you have mixed character and numeric variables for which the first 20 observations are all numeric.