Evolutionary tracks in the HR diagram of stellar models initially rotating with approximately 200 km s^-1, and with initial masses of 6, 7, 8, 9, 10, 12, 15, 20, 25, 30, 40, 50, 60, 70, 80, 100, 125, 150, 175, 200, 230, 260, 300, 400, and 500  M_⊙. Overlaid are lines (in blue) of constant nitrogen surface mass fraction, corresponding to nitrogen enhancement factors of 2, 5, 10, and 20, as indicated in blue. Lines of constant nitrogen enhancement factors of 2 and 3 corresponding to models with approximate initial rotational velocities of 150 and 100 km s^-1 are also shown.