0001130464-07-000140 8-K 3 20070423 8.01 9.01 20070424 20070423 BLACK HILLS CORP /SD/ 0001130464 4911 460458824 SD 1231 8-K 34 001-31303 07782650 625 9TH STREET PO BOX 1400 RAPID CITY SD 57709 6057212343 625 9TH STREET PO BOX 1400 RAPID SD 57709 BLACK HILLS HOLDING CORP 20001222 8-K 1 form_8k-valencia.htm BHC PURCHASE AGREEMENT WITH PNM GRAPHIC 2 ballot.jpg GRAPHIC EX-99 3 ex_99.htm NEWS RELEASE DATED 4-23-07