According to the National Council of Churches' 2011 Yearbook of American & Canadian Churches, the Seventh-day Adventist denomination reported a 4.31 percent growth rate in 2009. This makes the 1,043,606 member church the second fastest growing denomination in North America.
The top church, the Jehovah’s Witnesses, reported being up 4.37 percent. It has just slightly more members, with 1,162,686. The largest Protestant church in North America, the Southern Baptist Convention (the nation's second largest denomination), which has been "long a reliable generator of church growth, reported a decline in membership for the third year in a row, down .42 percent to 16,160,088 members. The Catholic Church, the nation's largest at 68.5 million members, reported a membership growth of .57 percent."
Mainline churches reporting declines in membership are United Church of Christ, down 2.83 percent to 1,080,199 members; the Presbyterian Church (USA), down 2.61 percent to 2,770,730 members; the Episcopal Church, down 2.48 percent to 2,006,343 members; the Evangelical Lutheran Church in America. down 1.96 percent to 4,542,868 members; the American Baptist Churches USA, down 1.55 percent to 1,310,505; the Lutheran Church (Missouri Synod), down 1.08 percent to 2,312,111 members; and the United Methodist Church, down 1.01 percent to 7,774,931 members.
Like Seventh-day Adventists, other American-born churches such as The Church of Jesus Christ of Latter-day Saints (6,058,907 members) and the Assemblies of God (2,914,669 members) reported 1.42 percent and .52 percent growth, respectively. Each of these numbers come from 2009, were reported in 2010, and have been published in the Yearbook this week.
h/t Ray Dabrowski