Religious worship is integral to the lives of millions of Americans. In this paper, I provide a descriptive analysis of religious worship attendance using geodata from smartphones for over 2 million Americans in 2019. I establish several key findings. First, 73% of people step into a religious place of worship at least once during the year on the primary day of worship (e.g. Sundays for most Christian churches). However, only 5% of Americans attend services “weekly”, far fewer than the ~22% who report to do so in surveys. The number of occasional vs. frequent attenders varies substantially by religion. I estimate that approximately 45M Americans attend worship services in a typical week of the year, but with large changes around Holidays (e.g. Easter). I document how start times, duration of attendance, and average household income all differ meaningfully across religious traditions. The intensity of religious observance correlates with a host of other activities. For example, relative to non-attenders and infrequent attenders, frequent religious attenders are less likely to go to strip clubs, liquor stores, and casinos. While cell phone data has limitations, this paper provides a unique way of understanding worship attendance and its correlates.