Holidays. Labor day Colorado first state in union to make Labor day a legal holiday. Post S 4 1949 mag.sec. p.3 3,000 organized workers march down 16th street in impressive, mile long Labor day parade. Post S 5 149 p.1 Social, political roles held vital for labor. Post S 5 '49 p.3 3500 Unionists March in Denver. News S 5 1950 p.26 Labor Day - then and today. Post Roundup S.2, '56, P.2