2008: Minnesota Nurses Association breaks off from the American Nurses Association, saying its members want a more forceful union that will represent the economic interests of bedside nurses.

March 2010: Nurses and 14 Twin Cities hospitals begin contract talks for a new three-year agreement. Hospitals seek concessions on pensions, health insurance and nurse staffing rules.

May 6: Nurses stage informational picketing, saying their proposal for formal nurse staffing ratios would improve patient care and hospital safety.

May 19: Nurses reject hospitals' offer and authorize a one-day strike.

June 4: Contract talks break down.

June 10: Nurses stage a 24-hour walkout at the 14 hospitals.

June 21: Nurses vote to authorize an open-ended strike, later set for July 6.

June 23: Federal mediator calls negotiators back to the bargaining table.

June 29: Hospitals make late-night concessions on condition that union leaders suspend the strike deadline and quickly endorse hospital offer. Union negotiators refuse, propose continuing to negotiate, but talks break down.

June 30: Mediator calls both sides back to the table; a deal is struck.