And during the time it was practiced there was a surplus of women. One reason for this was the fact that more women seemed to convert then men.
The period between the civil war and the statehood of Utah was somewhat unique in that the population imbalance was fueled by casualties of the war, particularly in Tennessee and along the lower Mississippi River. Mormon missionaries couldn't have had an easier job, offering some women their only viable chance to raise families, with the bonus of men who were not to get drunk.
Eventually, as a generation moves along, Utah boys become men and the practicality of polygamy becomes less. But did it really go away? The FLDS church is still alive. These splinter-group Mormons still believe in polygamy and until they run afoul of the law, their arrangements constitute cohabitation agreements in which only one wife is legally married. While polygamy is illegal throughout the United States, cohabitation is regulated strictly by the states and locales (if effectively at all after Lawrence v. Texas in 2003).
They do get busted, when someone claims sexual abuse, embezzlement of funds, attempt to get multiple marriage licenses, underage partners, cousin relationships, etc. But many who know the limitations don't get into trouble. Raids based solely on living arrangements are not a big issue today (are they?).