Found it on the DOT's website per Magicbus and his post
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?reg=392.62
Prohibited practices
§392.62 Safe operation, buses.
No person shall drive a bus and a motor carrier shall not require or permit a person to drive a bus unless—
(a) All standees on the bus are rearward of the standee line or other means prescribed in §393.90 of this subchapter;
(b) All aisle seats in the bus conform to the requirements of §393.91 of this subchapter; and
(c) Baggage or freight on the bus is stowed and secured in a manner which assures—
(c)(1) Unrestricted freedom of movement to the driver and his proper operation of the bus;
(c)(2) Unobstructed access to all exits by any occupant of the bus; and
(c)(3) Protection of occupants of the bus against injury resulting from the falling or displacement of articles transported in the bus.
[63 FR 33278, June 18, 1998]
Doesn't specifically say strollers which is why I can see some places using their own guidelines to address the issue.
http://www.fmcsa.dot.gov/rules-regulations/administration/fmcsr/fmcsrruletext.aspx?reg=392.62
Prohibited practices
§392.62 Safe operation, buses.
No person shall drive a bus and a motor carrier shall not require or permit a person to drive a bus unless—
(a) All standees on the bus are rearward of the standee line or other means prescribed in §393.90 of this subchapter;
(b) All aisle seats in the bus conform to the requirements of §393.91 of this subchapter; and
(c) Baggage or freight on the bus is stowed and secured in a manner which assures—
(c)(1) Unrestricted freedom of movement to the driver and his proper operation of the bus;
(c)(2) Unobstructed access to all exits by any occupant of the bus; and
(c)(3) Protection of occupants of the bus against injury resulting from the falling or displacement of articles transported in the bus.
[63 FR 33278, June 18, 1998]
Doesn't specifically say strollers which is why I can see some places using their own guidelines to address the issue.