Wondering why the roads and trains seemed crowded in June? Well, it may be because the state’s employers added an estimated 21,400 jobs that month, compared to May.

It was the best month-over-month increase in two years for the state, and represents about one third of all the state’s job growth in the past year. The construction sector — which added 2,300 jobs in the month, a 1.4 percent increase — was again the strongest performing industry. But most sectors saw job growth.

The US Bureau of Labor Statistics said Massachusetts had the strongest job growth of any state last month, both in terms of the total number of jobs and the percentage increase (0.6 percent).


Meanwhile, the state’s unemployment rate remained steady at 3.5 percent in June, compared to a national rate of 4 percent.

(Obligatory disclaimers: These numbers are preliminary, and have been adjusted to reflect seasonal hiring patterns.)

Jon Chesto can be reached at jon.chesto@globe.com. Follow him on Twitter @jonchesto.