In the census, the state is placed 21st on the population chart, followed by Tripura at 22nd place. Kangra District was top ranked with a population strength of 1,507,223 (21.98%), Mandi District 999,518 (14.58%), Shimla District 813,384 (11.86%), Solan District 576,670 (8.41%), Sirmaur District 530,164 (7.73%), Una District 521,057 (7.60%), Chamba District 518,844 (7.57%), Hamirpur district, Himachal Pradesh 454,293 (6.63%), Kullu District 437,474 (6.38%), Bilaspur district, Himachal Pradesh 382,056 (5.57%), Kinnaur District 84,298 (1.23%) and Lahaul and Spiti 31,528 (0.46%).. How many districts have a population of over 500000?