elected only four after 1965. This was done to preserve the ideal of having whole counties represented by a single Senator, rather than breaking counties up into multiple districts. A constitutional amendment in 1972 expanded the Senate to 47 members, elected from districts proportional to the population. These districts are reapportioned every ten years based on the United States Census to ensure they remain proportional. Powers and legislative process The Maryland Senate, as the upper house of the bicameral Maryland General Assembly, shares with the Maryland House of Delegates the responsibility for making laws in the state of Maryland. Bills are often developed in the period between sessions of the General Assembly by the Senate's standing committees or by individual senators. They are then submitted by senators to the Maryland Department of Legislative Services for drafting of legislative language. Between 2000 and 2005, an average of 907 bills were introduced in the Senate annually during the three-month legislative session. The bill is submitted, and receives the first of three constitutionally mandated readings on the floor of the Senate, before being assigned to a committee. The decision about whether legislation passes is often made in the committees. Committees can hold legislation and prevent it from reaching the Senate floor. The recommendations of committees on bills carry tremendous weight; it is rare for the Senate as a whole to approve legislation that has received a negative committee report. Once a committee has weighed in on a piece of legislation, the bill returns to the floor for second hearing, called the "consideration of committee" report, and a third hearing, which happens just before the floor vote on it. Once passed by the Senate, a bill is sent to the House of Delegates for consideration. If the House also approves the bill without amendment, it is sent to the Governor. If there is amendment, however, the Senate may either reconsider the bill with amendments or ask for the establishment of a conference committee to work out differences in the versions of the bill passed by each chamber. Once a piece of legislation approved by both houses is forwarded to the Governor, it may either be signed or vetoed. If it is signed, it takes effect on the effective date of the legislation, usually October 1 of that year. If it is vetoed, both the Senate and the House of Delegates must vote by a