Greatest Hits, Vol. 2 covers Alan Jackson’s singles output between 1996 and 2004, a period that saw him grow from a reliable Nashville hit maker into one of modern country’s elder statesmen. Even as he grew older, Jackson’s personality and music remained essentially the same. “Little Bitty” and “It’s Five O’Clock Somewhere” are definitive Jackson: charming and catchy, but heartfelt and never cloying. Even though Jackson had been singing dance songs about infidelity since the beginning of his career, 1997’s “Who Cheatin’ Who” (itself a cover of a 1980 hit by Charly McClain) showed that the form had lost none of its possibility. As he grew older, Jackson also added new kinds of songs to his repertoire. “Remember When” is a rumination on decades of marriage, and it requires a singer with a depth of life experience. “Where Were You (When the World Stopped Turning)” was even more crucial to Jackson’s development. At a time when America was frenzied by finger-pointing, Jackson had the maturity and courage to release the most genuinely compassionate song of the post-9/11 moment.