One significant cause of the decline in Episcopal attendance in recent years is, of course, the schism that began after the General Convention of 2003 consented to the election of the Rt. Rev. Gene Robinson, an openly gay man in a relationship, as Bishop of New Hampshire.
In the following decade, five diocesan conventions voted to leave the Episcopal Church: Fort Worth, Pittsburgh, Quincy, South Carolina, and San Joaquin. Some congregations in each diocese remained with the Episcopal Church, effectively splitting each diocese. The small remnant of the Diocese of Quincy was absorbed by the Diocese of Chicago; ASA in the other four dioceses all declined 70 to 80 percent in the past decade, by far the worst declines in the church. (These statistics, drawn from the parochial reports filed by every Episcopal church, are available from the Research and Statistics section of episcopalchurch.org.)
The departures had a dramatic effect in those dioceses, and individual parishes elsewhere in the country have also left the Episcopal Church. Most of the departing dioceses and congregations have joined the Anglican Church in North America (ACNA), founded in 2009. But nationally, ACNA is dwarfed by the Episcopal Church. Based on reports from the two churches, ACNA had 111,853 members, while the Episcopal Church was 16 times larger, with 1,779,335 baptized members.
Still, ACNA membership is growing, while Episcopal numbers are declining. With declining attendance comes declining revenues. The church does not exist for the purpose of making money, of course — but eventually money has a kind of veto power. If a church fails to pay the electric bill for enough months in a row, the lights will be turned off.
Real estate poses a particular problem for cash-strapped congregations and dioceses.