FIRST THE rural counties and then at mid-century the city of Baltimore wielded the political power in Maryland's state legislature. But now the swelling populations of Maryland's suburbs--Baltimore County, Montgomery, Prince George's, Anne Arundel and Howard--have shifted the power their way. Though righting the "Baltimore Tilt" has taken longer than it should have, the state senators and delegates from these counties have sharpened their collective political skills enough to win key legislative positions.

Seniority helps. But the emergence of suburban lawmakers was for too long thwarted by their lack of savvy: how and when to rally around issues instead of going off in different directions, how to work with smaller counties when interests coincide and how to pick battles that are worth it. This is how the short lists of House and Senate leaders now include growing numbers of suburban lawmakers:

In the House of Delegates, the majority leader is John Hurson of Chevy Chase. In the Senate, the president is Mike Miller of Clinton. Throughout the committees in both chambers, the rosters show heavier representation of the big counties.

Only days ago, two Montgomery senators were put forth for top positions in the session that begins Jan. 12. Sen. Ida G. Ruben will take over the No. 2 spot--president pro tem. Sen. Chris Van Hollen of Kensington will take her spot as vice chair of the Budget and Taxation Committee.

With the ascendancy of Maryland's suburbs comes responsibility to exercise the legislative powers fairly. Montgomery and Prince George's lawmakers know from past experience what it is like to be left in the legislative lurch. They have won the leadership fairly and have huge needs to tend. But their responses need not and should not come at the expense of necessary programs and services in Baltimore City or the state's smaller, poorer counties.