BOVINE TUBERCULOSIS (BTB) IS AN IMPORTANT AGRICULTURAL DISEASE FROM BOTH AN ECONOMIC AND A PUBLIC HEALTH PERSPECTIVE. MYCOBACTERIUM BOVIS, THE CAUSE OF BTB HAS A WIDE HOST RANGE INCLUDING CATTLE, WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS), AND HUMANS, AND CAUSES DECREASED MILK AND MEAT PRODUCTION IN CATTLE. HUMANS CAN BECOME INFECTED BY CONTACT WITH INFECTED ANIMALS OR, MORE COMMONLY THROUGH CONSUMPTION OF UNPASTEURIZED MILK. RISK OF ZOONOTIC BTB INFECTION HAS BEEN GREATLY REDUCED IN DEVELOPED COUNTRIES BY A COMBINATION OF EFFECTIVE TEST AND SLAUGHTER CONTROL PROGRAMS AND MILK PASTEURIZATION; HOWEVER, M. BOVIS IS STILL RESPONSIBLE FOR 1-2% OF HUMAN TUBERCULOSIS CASES IN THE US. DUE TO THE RISK OF ZOONOTIC INFECTION, AND THE PRODUCTION LOSSES CAUSED BY BTB, THE US INSTITUTED A BTB ERADICATION PROGRAM IN 1917. THIS PROGRAM INCLUDES SLAUGHTER SURVEILLANCE, AND A LENGTHY TESTING PROTOCOL FOR INFECTED HERDS ESTIMATED TO COST OVER $1.5 MILLION IN A 1000 COW DAIRY HERD. DESPITE OVER 100 YEARS OF DIRECTED NATIONAL CONTROL, OUTBREAKS STILL OCCUR IN CATTLE EVERY YEAR.THERE ARE TWO EXPLANATIONS FOR THE DIFFICULTY IN ELIMINATING BTB. FIRST, BTB INFECTION IN CATTLE REMAINS SUBCLINICAL, AND POTENTIALLY UNDETECTED FOR MONTHS TO YEARS UNTIL LESIONS BECOME LARGE ENOUGH TO IMPAIR ORGAN FUNCTION. SECOND, THERE ARE MULTIPLE SOURCES OF BTB INFECTION IN CATTLE INCLUDING SPILLOVER FROM WILDLIFE, ANIMAL MOVEMENT, ZOONOTIC TRANSMISSION, AND FOMITE TRANSMISSION. THE ONLY KNOWN WILDLIFE RESERVOIR OF BTB IN THE US IS A POPULATION OF WHITE-TAILED DEER IN MICHIGAN, AND CROSS SPECIES TRANSMISSION REMAINS AN IMPORTANT SOURCE OF CATTLE INFECTION THERE. CATTLE TRADE BETWEEN MEXICO AND THE US IS COMMON AND BTB PREVALENCE IS 14.2% IN SOME REGIONS IN MEXICO. MOVEMENT OF ANIMALS FROM MEXICO TO THE US COULD RESULT IN TRANSMISSION; HOWEVER, ANIMAL MOVEMENT AND WILDLIFE DO NOT ACCOUNT FOR ALL OUTBREAKS IN THE US. REMAINING CASES MAY BE LINKED TO ZOONOTIC TRANSMISSION.BECAUSE OF THE POTENTIAL LAG TIME BETWEEN INFECTION AND DETECTION, AND BECAUSE OF THE MULTIPLE POSSIBLE SOURCES OF INFECTION, IDENTIFYING THE SOURCE OF INFECTION IN A HERD ARE DIFFICULT. ALTHOUGH THOROUGH SAMPLING IS ROUTINE IN TRACEBACK INVESTIGATIONS, ANIMAL MOVEMENT RECORDS ARE OFTEN INCOMPLETE, AND OTHER POTENTIAL SOURCES OF INFECTION, INCLUDING ZOONOTIC TRANSMISSION, ARE DIFFICULT TO CHARACTERIZE. TO MAXIMIZE THE INFORMATION AVAILABLE FROM OUTBREAK INVESTIGATIONS, WHOLE GENOME SEQUENCING (WGS) OF M. BOVIS ISOLATES FROM INFECTED HERDS WAS INCORPORATED INTO THE BTB ERADICATION PROGRAM BY THE NATIONAL VETERINARY SERVICES LABORATORIES IN 2013. WE WILL FILL A CRITICAL GAP IN DETERMINING THE SOURCE OF AN OUTBREAK BY PREDICTING TIME AND LOCATION OF INFECTION. OUR OBJECTIVE IS TO UTILIZE M. BOVIS WGS DATA TO INCREASE EFFICIENCY IN OUTBREAK INVESTIGATIONS BY 1) ESTIMATING TIME SINCE HERD INFECTION AND DRIVERS OF VARIATION IN M. BOVIS EVOLUTIONARY RATE, AND 2) PREDICTING THE GEOGRAPHICAL SOURCE OF OUTBREAKS BY ANALYZING PAN-GENOMIC POPULATION STRUCTURE.