29 CFR 776.12: Employees traveling across State lines.

Questions are frequently asked as to whether the fact that an employee crosses State lines in connection with his employment brings him within the Act's coverage as an employee “engaged in commerce.” Typical of the employments in which such questions arise are those of traveling service men, traveling buyers, traveling construction crews, collectors, and employees of such organizations as circuses, carnivals, road shows, and orchestras. The area of coverage in such situations cannot be delimited by any exact formula, since questions of degree are necessarily involved. If the employee transports material or equipment or other persons across State lines or within a particular State as a part of an interstate movement, it is clear of course, that he is engaging in commerce. 47 And as a general rule, employees who are regularly engaged in traveling across State lines in the performance of their duties (as distinguished from merely going to and from their homes or lodgings in commuting to a work place) are engaged in commerce and covered by the Act. 48 On the other hand, it is equally plain that an employee who, in isolated or sporadic instances, happens to cross a State line in the course of his employment, which is otherwise intrastate in character, is not, for that sole reason, covered by the Act. Nor would a man who occasionally moves to another State in order to pursue an essentially local trade or occupation there become an employee “engaged in commerce” by virtue of that fact alone. Doubtful questions arising in the area between the two extremes must be resolved on the basis of the facts in each individual case.