The American Pipit is similar to the Sprague's Pipit but the Sprague's Pipit has much less streaking on the underparts, more streaking on the back, a paler face, and pink legs. The Sprague's Pipit is easiest to identify by its call since it is rarely observed on the ground. It often calls upon being flushed. The rare Red-throated Pipit (breeds in Alaska and rare migrant in California) has a different call and more streaking on the underparts. Sparrows and longspurs can be found in similar habitats but have thick, conical bills.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.